Islam and the Qur’an

A Reformed Theological Analysis

Introduction

Islam is a major world religion founded in the 7th century by the prophet Muhammad, whose teachings are recorded in the Qur’an. From a Reformed Protestant theological perspective grounded in the Bible and articulated in the historic confessions of the Reformation, Islam represents a distortion of biblical truth. The Protestant Reformers and their theological heirs (the Puritans and Reformed theologians) viewed Islam not as a brand-new revelation but essentially as a Christian heresy, a composite of borrowed elements from Judaism and Christianity mixed with significant departures from core biblical doctrines . John Calvin described Islam as a “defection” from Christianity that “turn[ed] [its followers] from Christ”, noting that it spread widely by tearing people away from the church . Heinrich Bullinger (1504–1575) likewise classified Muhammad’s teaching as a combination of old heresies: a denial of the Trinity and of Christ’s atoning work (like the ancient Arian and Pelagian heresies) and an affirmation of salvation by human works . In short, Islam “picks and chooses” from biblical faith, affirming one God and some moral precepts but rejects central truths of Christianity such as the Trinity, the incarnation and divinity of Christ, and the necessity of atoning grace . This paper will examine the flawed theology of Islam and the Qur’an from a Reformed perspective, highlighting these key doctrinal issues. It will also consider the textual transmission of the Qur’an (including early manuscript variants), the role of Hadith literature, and the multitude of sects within Islam, all in contrast with the unity and finality of biblical revelation as understood in Reformed theology. The goal is a thorough, fair, and truthful assessment of Islamic theology’s core flaws in light of Scripture and Reformed doctrine, drawing on authorities such as Dr. James R. White, the English Puritans and Reformed confessions, John Calvin’s Institutes, Greg Bahnsen’s apologetic insights, and, above all, the teachings of the Old and New Testaments.

The Doctrine of God: Trinity vs. Tawhid

At the heart of Islam is an uncompromising monotheism (tawhid), the belief that God (Allah) is one in essence and person. The Qur’an emphatically rejects the Christian doctrine of the Trinity, misunderstanding it as a form of polytheism. In fact, the Qur’an’s only direct reference to a “Trinity” presents a gross distortion: “Allah, Mary, and Jesus” are cited as if Christians worship three separate beings (cf. Surah Al-Ma'idah - 116). Dr. James White notes that “the writer of the Qur’an [never] understood what the doctrine of the Trinity was”, since it polemicizes against a triad of God, Jesus, and Mary implying that Christians believe God took a wife (Mary) who bore a son (Jesus) . This misrepresentation of Christian belief in the Qur’an is a theological flaw of the first order, indicating that the Qur’an’s author did not grasp the true doctrine of “Father, Son, and Holy Spirit.” According to James White, Islam therefore holds a deep “misunderstanding of the Trinity”, which leads Muslims to accuse Christians of polytheism . The Qur’an’s denial that God has a Son (e.g. Surah An-Nisa - 171) falls into what the Apostle John defined as the “antichrist” position: “This is the antichrist, he who denies the Father and the Son” . By rejecting God’s Trinitarian nature and the divine Sonship of Christ, Islamic theology (in the Reformed Christian view) repudiates God’s self-revelation and thus “does not have” the true God, for “no one who denies the Son has the Father” (1 John 2:23).

Reformed theology insists on the doctrine of the Holy Trinity: one God in three coeternal persons, as taught in Scripture and summarized in confessions like the Westminster and Belgic Confessions. The Westminster Confession (1646) affirms that “in the unity of the Godhead there be three Persons, of one substance, power, and eternity, God the Father, God the Son, and God the Holy Ghost” (WCF II.3). Islam’s Unitarian monotheism (affirming only a single-person God) is therefore viewed as a serious departure from the true knowledge of God. The Reformers often compared Islam to the ancient Arian heresy (which denied Christ’s full deity) . They did not consider Islam a brand-new faith but “a heretical deviation” – essentially an offshoot of Christianity that “rejects… the doctrines of the Trinity and of the incarnation” while retaining a form of monotheism . From a Reformed standpoint, because “their rock is not as our Rock” (Deuteronomy 32:31), the Allah of the Qur’an – conceived as a solitary monad cannot be equated with the Triune God revealed in Scripture. The Puritan theologian John Owen, like many Protestant divines, identified any denial of the Trinity or of Christ’s deity as essentially antichristian. Reformed apologist Greg Bahnsen likewise noted Islam’s “unitarianism” as a “pivotal” difference that makes its concept of God internally problematic . Because Islam so emphasizes God’s absolute transcendence (tanzīh) and oneness, some Muslim theologians conclude that no human language can adequately describe Allah . Ironically, as Bahnsen observes, this extreme apophatic theology would “rule out what the Qur’an claims to be”, a comprehensible revelation from God . In sum, Islam’s flawed doctrine of God lies in rejecting the Trinity, a truth essential to God’s identity and replacing it with a monadic deity who, in Reformed eyes, cannot relationally love or save as the triune God does (since, for example, a solitary God had no eternal object of love or fellowship until creating creatures). This deviation has cascading effects on all other areas of theology.

Scripture and Revelation: The Bible vs. the Qur’an

Authority and Sufficiency of Scripture. A second fundamental flaw in Islam from the Reformed perspective concerns revelation and religious authority. The Christian faith, especially as codified by the Reformers, holds that God’s special revelation to mankind was completed in the Scriptures of the Old and New Testaments. The Bible is “the whole counsel of God” containing all things necessary for God’s glory and man’s salvation, “unto which nothing at any time is to be added, whether by new revelations of the Spirit or traditions of men” (WCF I.6) . By contrast, Islam teaches that after Biblical times God sent a new revelation, the Qur’an superseding and correcting the Bible. Muslims revere the Qur’an (in Arabic) as the literal Word of God delivered to Muhammad, and they claim previous scriptures were corrupted over time . In effect, Islam denies the sufficiency and preservation of the Bible, asserting that the final and perfect message is in the Qur’an alone.

Reformed theologians strongly contest this claim on both theological and historical grounds. John Calvin pointed out that Muslims go astray “not keeping themselves fast enclosed within the bounds of Holy Scripture”. He faulted Islam’s “faulty doctrine of Scripture”, akin to that of later sects like the Mormons, for adding an ostensible new holy book and rejecting the completed revelation of God in the Old and New Testaments . The Reformers noted that the Qur’an itself, while accusing Jews and Christians of altering their scriptures, “purports to retain the original revelation of God given in the Old and New Testaments” . In fact, the Qur’an acknowledges the Torah (Tawrat), Psalms (Zabur) and Gospel (Injil) as earlier genuine revelations from Allah (see Surat Al-Ma'idah [5:44-48]). This presents an internal dilemma: the Qur’an claims to confirm those previous scriptures, yet it simultaneously contradicts their core teachings. Dr. James White highlights, for example, that the Qur’an flatly denies Jesus’ crucifixion (Surah An-Nisa - 157) and misunderstands the Trinity, thereby departing from the very biblical truth it supposedly affirms . Greg Bahnsen formulates the dilemma pointedly: “The Koran acknowledges the words of Moses, David, and Jesus to be the words of prophets sent by Allah – in which case the Koran may be, on its own terms, refuted because of its contradictions with earlier revelation” . In other words, if the Bible is truly God’s Word, the Qur’an’s opposing claims cannot be true; yet if (as Muslims assert) the Bible was corrupted, it raises the question of why the Qur’an in places tells the “People of the Book” to hold to their Scriptures (e.g. Surat Al-Ma'idah) and never explicitly states that the text of the Torah/Gospel was falsified. This self-contradiction – affirming previous revelation from God while teaching doctrines at odds with it – is viewed by Christians as a fatal flaw in Islam’s foundations . It is one reason early Christian polemicists like John of Damascus (8th century) labeled Islam a “heresy” rather than a brand-new religion: “this man [Muhammad]… having chanced upon the Old and New Testament… devised his own heresy”, borrowing from and deviating from the Bible .

Biblical Warnings of “Another Gospel.” From a biblical perspective, Islam’s very emergence is seen as falling under the apostolic warnings about false revelations. The Apostle Paul admonished the Galatians that “even if we or an angel from heaven should preach… a gospel contrary to the one we preached to you, let him be accursed”(Galatians 1:8) . Christians have often noted the eerie relevance of this verse: according to Islamic tradition, Muhammad’s revelations began with an angel (identified as Jibril/Gabriel) appearing to him in a cave, delivering a message that diverged from the New Testament gospel of Christ’s finished work. Paul’s hypothetical scenario became historical reality in Islam, from the Christian viewpoint. Thus the Reformed tradition regards Muhammad as a false prophet bringing a false gospel, a later claimant whose teachings do not accord with the already attested revelation of God’s Son. The Protestant confessions echo this by asserting there can be no new word from God after Scripture. The Westminster divines wrote that God’s written Word is so complete that “nothing at any time is to be added”, explicitly rejecting “new revelations of the Spirit” alongside Scripture . The 16th-century Belgic Confession likewise states that the Bible is the final Word of God, such that “no one… may claim to have more authority than these holy Scriptures”(Belgic Conf., Art. 7). Any religion that introduces another scripture as superior, be it the Qur’an, Book of Mormon, etc. is seen as violating this principle. The Reformers unapologetically concluded that Islam’s Qur’an is a counterfeit revelation, one that cannot be reconciled with the God-breathed Scripture that came before. Indeed, many applied 1 John 4:1–3 to Islam’s denial of Christ’s incarnation: “every spirit that does not confess Jesus Christ come in the flesh is not of God,” implying that the spirit behind such teaching is “the spirit of antichrist.” By these biblical tests, Islam falls short.

Christ and Salvation: The Person and Work of Christ Denied

Perhaps the most consequential theological divide between Islam and Reformed Christianity concerns the person and work of Jesus Christ. In Christian theology, Jesus is the incarnate Son of God, fully God and fully man who died on the cross as an atoning sacrifice for sin and rose again for our justification. Salvation is by God’s grace alone, on the basis of Christ’s redemptive work, received through faith alone (Ephesians 2:8–9). Islam, however, while revering Jesus (ʿĪsā) as a notable prophet, explicitly denies His deity, His sonship, and His atoning death. The Qur’an’s theology cannot tolerate the idea that God would become man (it rejects the incarnation) or that the Messiah would be crucified as a curse (it claims Jesus was not actually killed on the cross, Qur’an 4:157). In Islamic doctrine, Jesus is not Lord or Savior, but a human messenger who prepared the way for Muhammad, the final prophet. Moreover, Islam denies the concept of original sin and the need for a sin-bearing Savior: each person is born morally neutral and can attain paradise by submitting to Allah and performing good works (alongside Allah’s mercy). No substitutionary atonement exists in Islamic theology; personal righteousness and divine forgiveness apart from any satisfaction of justice are the path to salvation.

From a Reformed perspective, these beliefs strike at the heart of the Gospel and reveal a theologically fatal flaw in Islam. The Reformers observed that Islam in essence revived the ancient Arian error (denying Christ’s deity) and Pelagian error (denying human depravity and salvation by grace) . Bullinger, for instance, wrote that Islam’s teaching “approach[es] paganism” in how far it goes in rejecting Christ’s divine mediation . The incarnation – God the Son taking on flesh is central to Christianity; the Qur’an’s rejection of this truth (and apparent confusion about it, as noted earlier) leaves Islam with a God who is distant and unapproachable, not Emmanuel (“God with us”). The atonement is likewise central to Christianity; by rejecting Jesus’ sacrificial death and resurrection, Islam leaves mankind with no savior and no sufficient payment for sin. As Dr. James White observes, Islam fundamentally misunderstands the incarnation, and thus fails to see why Christ’s death and resurrection are necessary . James White has engaged in many dialogues with Muslims, demonstrating what he calls the “flaws” in Islamic theology, notably Islam’s misapprehension of the Trinity and the incarnation of Christ. These errors have enormous soteriological consequences.

Greg Bahnsen provides an incisive internal critique: “the Islamic worldview teaches that God is holy and just toward sin, but… there can indeed be ‘salvation’ where guilt remains unremitted by the shedding of blood of a substitute for the sinner” . Islam claims Allah is just and hates sin, yet in Islamic doctrine no objective atonement is provided to satisfy divine justice. Sinners simply hope in Allah’s mercy and attempt to outweigh bad deeds with good. Bahnsen points out the inconsistency: “The legalism of Islam (good works weighed against bad) does not address this problem because a person’s previous bad works are not changed by later good ones, but continue on one’s record in the sight of Allah (who supposedly cannot tolerate sin but must punish it)” . The Bible had already declared, “without the shedding of blood there is no forgiveness of sins” (Hebrews 9:22), and taught that only a flawless substitute (Christ, the Lamb of God) could bear God’s wrath in our place (Isaiah 53, 1 Peter 2:24). By denying the need and fact of the cross, Islam leaves a glaring gap in how God’s justice and mercy can be reconciled. Reformed theologians insist that God’s holiness demands punishment for sin – either laid upon Christ or borne by the sinner. Since Islam rejects Christ’s atoning sacrifice, it effectively denies the only hope of salvation, leaving its adherents under the full weight of the law. The Westminster Confession of Faith (Chap. VIII) states that it is “impossible” for sinners to find acceptance with God except through the mediation of Christ, who fulfilled all righteousness and made satisfaction for sin. Any system (such as Islam) that bypasses Christ’s mediatorial work is deemed a theologically false remedy for man’s fallen condition.

Moreover, the denial of Jesus’ divine Sonship in Islam (Surah At-Tawbah declares it blasphemy to say “Jesus is the Son of God”) is seen by Christians as a direct assault on God’s revelation of Himself. It is not a trivial doctrinal difference but, according to Scripture, a hallmark of antichrist teaching . The Apostle John wrote: “Who is the liar but he who denies that Jesus is the Christ? He is the antichrist who denies the Father and the Son” (1 John 2:22). By explicitly rejecting Jesus as the Son, Islam by biblical definition speaks with an antichrist spirit – severing its followers from the Father, since “no one who denies the Son has the Father” (1 Jn 2:23). The Puritan divines frequently identified the religion of “Mahomet” (Muhammad) as a manifestation of this spirit of antichrist, because it so strenuously opposes the core truths of Christ’s identity and work. They also noted the moral example of Islam’s prophet as contrary to the holiness of Christ, for instance, Muhammad as a warrior and polygamist was contrasted with Jesus’ sinless life, though the primary concern was doctrinal faithfulness. In sum, from the Reformed standpoint, Islam’s theology of Christ and salvation is fundamentally flawed: it has “a form of godliness” (belief in one God, affirmation of prophets) but denies the power of the Gospel – the person of Christ as God incarnate and the power of His cross and resurrection (2 Timothy 3:5, 1 Corinthians 1:18).

Textual Integrity: The Qur’an’s Preservation and Early Variants

Muslims commonly assert that the Qur’an has been perfectly preserved since Muhammad – letter for letter, word for word – in contrast (they claim) to the Bible, which they view as textually corrupted. However, modern manuscript research and even early Islamic sources tell a more complicated story, revealing textual variants and editorial efforts in the early Quranic text. The Reformed apologists who engage Islam point out that the idealized Muslim narrative of an untouchable Qur’anic text is historically questionable. Dr. James White, in What Every Christian Needs to Know about the Qur’an, devotes a chapter to the history of the Qur’anic text and highlights that there have indeed been textual variants . While none of these variants may drastically change the overall message of the Qur’an, their existence undermines the absolutist claim that every letter of today’s Qur’an is exactly as revealed to Muhammad.

Islamic tradition itself records a significant event a couple of decades after Muhammad: the standardization of the Qur’an under Caliph ʿUthmān (c. 653 AD). According to Sahih al-Bukhari (the most authoritative Sunni Hadith collection), differences in recitation among Muslim communities alarmed ʿUthmān. He commissioned an official copy of the Qur’an from Muhammad’s scribal companions and then ordered that “all the other Qur’anic materials, whether written in fragmentary manuscripts or whole copies, be burnt.” . This famous hadith (Bukhari 4987) relates how ʿUthmān sent a standardized copy to each province and destroyed variant copies to prevent further conflict . Such an action is telling: it acknowledges that multiple versions or at least divergent textual traditions of the Qur’an existed (e.g. the codices of companions like Ibn Masʿud and Ubayy ibn Kaʿb, which reportedly differed in arrangement and even content). The result was the ʿUthmānic codex – essentially the basis of today’s Qur’an, but at the cost of suppressing other parallel traditions. Reformed scholars argue that this history contradicts the popular Muslim notion that the Qur’an was uniform and miraculously preserved without human intervention. In fact, it was an exercise of textual criticism and authoritative editing not unlike how other texts of antiquity were gathered.

Recent scholarly studies and manuscript discoveries have further illuminated the textual variation in early Qur’ans. For example, the Ṣanʿā’ palimpsest (discovered in Yemen) contains an earlier Quranic text underneath a later one, showing numerous minor variants compared to the standard text . Radiocarbon dating places some of these fragments in the 7th century. An edition of the Ṣanʿā’ manuscript’s lower text, published in 2012, revealed “many variants” from the Uthmanic version . Scholars like Dr. Keith Small (2011) have compared early Qur’an manuscripts and conclude that “there never was one original text of the Qur’an” in Muhammad’s time; rather, there were multiple concurrent texts that were eventually edited and unified . Small notes that ʿUthmān’s elimination of rival codices “removed many texts which had equally good claims” to authenticity, and that for a period there were “50 different ways” of reciting the Qur’an before standardization . In other words, far from being immune to textual history, the Qur’an went through a “process of development and improvement” over at least a century or more . Modern Muslims still recognize seven to ten qirā’āt (canonical reading traditions) of the Qur’an, which are essentially sanctioned variants in pronunciation and slight wording. Even between the two most common readings today (Hafs vs. Warsh), one can count hundreds of small differences (usually vowels or diacritics altering meaning subtly). While devout Muslims see this as part of a divine plan (seven “modes” of the Qur’an were mentioned in hadith), from an outside perspective it confirms that variation existed and persists.

The Protestant polemicists often compare this with the Bible’s manuscript tradition. Ironically, Christians freely acknowledge textual variants in biblical manuscripts and through the science of textual criticism have largely identified and corrected copyist errors, so that we are confident in  the Bible’s text. The existence of variant readings doesn’t nullify inspiration; it simply reflects the reality of transmission by human scribes, which textual scholars work through (a process guided by the sheer abundance of manuscript evidence for the Bible). Muslims have historically been less open about Quranic variants, often claiming there are none of significance. But as evidence mounts, Muslim scholarship (e.g. at institutions like Al-Azhar or in works by scholars like Shady Nasser) has begun to admit that minor textual variants and copyist mistakes occurred in Quranic manuscripts, though they maintain the overall preservation of the message. Reformed apologists seize on this to show a double standard: Muslims critique the Bible’s manuscript variants but ignore or deny the Qur’an’s. Dr. White, in debates, has pressed Muslims to account for the famous hadiths which speak of verses of the Qur’an being lost. For example, one narration from ʿĀ’ishah (Muhammad’s wife) recounts that a verse about stoning adulterers and a verse about adult foster-breastfeeding had been revealed and written on a leaf, but after Muhammad’s death “a tame sheep came in and ate it” while the household was distracted . (This hadith in Sunan Ibn Mājah is considered weak by many scholars , but it is widely cited in polemics.) Authentic or not, there are also hadiths of abrogation where certain revealed verses were “abrogated” in recitation, meaning they were once part of the Qur’an’s text but later removed (Islamic teaching holds that Allah could cause verses to be forgotten or replaced, per Qur’an 2:106). The Sahih Muslim collection mentions, for instance, that a verse prescribing ten foster-suckle events for establishing kinship was in the Qur’an but then was abrogated to five, and eventually not recited . All of this suggests to the critical observer that the Qur’anic text did undergo change and editing in its early decades.

For the Reformed apologist, this is significant in countering the Islamic assertion that only the Qur’an is pure while the Bible is textually corrupted. On the contrary, we argue that God in His providence preserved the Bible far better than the caricature suggests (the Old and New Testaments are supported by thousands of manuscripts and have a high degree of stability), and that the Qur’an’s history is not one of miraculous perfect preservation either. Moreover, the Bible was completed six centuries before the Qur’an and bears the marks of fulfilled prophecy and consistency that validate it as God’s Word, whereas the Qur’an, coming later, frequently misrepresents or contradicts biblical revelation, further discrediting its claim to be from the same God. A classic example: the Qur’an (in Maryam 19:28) seems to confuse Mary the mother of Jesus with Miriam the sister of Moses (calling Mary “sister of Aaron”), a likely error picked up from conflated traditions and gnostics. This and other anachronisms are difficult to reconcile with divine inspiration from a biblical standpoint.

In summary, the Reformed critique of the Qur’an’s text is that it is neither miraculously preserved beyond any textual variation, nor in harmony with prior Scripture. Instead, it appears as a historical document reflecting earlier religious ideas filtered through Muhammad’s understanding, subject to compilation and standardization like other writings. As Calvin wrote, “Mahomet has reported himself to be the party that should bring the full revelation – over and besides the Gospel”, driven by a “devilish curiosity” not content with Scripture . The Reformers saw the Qur’an as added human words claiming divine sanction, leading millions astray from the genuine Gospel of Christ.

The Hadith and the Multitude of Islamic Sects

The Role of Hadith. In Islam, doctrinal and practical guidance is not derived from the Qur’an alone. The Hadith – collections of reported sayings and actions of Muhammad and his companions are indispensable to understanding and implementing Islam. Sunni Muslims recognize six canonical hadith collections (with Sahih al-Bukhari and Sahih Muslim being the most esteemed), while Shi’a Muslims have their own hadith compilations (e.g. Al-Kafi, etc.) focusing on the sayings of the Prophet and their Imams. The Hadith literature governs everything from how to pray and perform ablutions, to legal and social norms, since the Qur’an by itself often gives only broad principles. However, the Hadith corpus is massive, complex, and fraught with authenticity challenges. Early on, Muslims had to develop sciences of hadith criticism to sift genuine traditions from pious fabrications. Thousands of hadiths are classified as “weak” or even “forged.” This reality means that a great deal of what Muslims consider part of their religion (the details of daily practice, law, theology, etc.) rests on fallible reports, not on the unambiguous Word of God. Reformed analysts point out that this undermines the claim of a clear, self-sufficient revelation in Islam. By contrast, Reformed Christianity holds to Sola Scriptura, Scripture alone as the final authority. There is no parallel in Christianity to the Hadith that holds canonical authority over believers’ lives (traditions in Christianity are subordinate and not considered revealed truth on par with Scripture). The dependence of Islam on the Hadith thus constitutes a structural flaw: the Qur’an may be held as perfect, but in practice one cannot follow Islam without the hadith – which are human transmissions, inevitably prone to error and dispute.

Sectarian Divisions. The necessity of the Hadith partly explains the proliferation of Islamic sects and schools. From the start, questions about leadership and whose narratives to trust led to a major schism: the Sunni-Shi’a split. This split began as a political conflict over succession (Sunnis recognized the caliphs starting with Abu Bakr; Shi’ites believed Muhammad’s family, especially Ali and his descendants, had the divine right to lead). But over time it developed into distinct theological and legal traditions. Sunni Islam (about 85–90% of Muslims today ) has four main schools of jurisprudence (Hanafi, Maliki, Shafi’i, Hanbali) and two major schools of theology (Ash’ari/Maturidi vs. Salafi/Athari). Shi’a Islam (10–15% of Muslims, predominant in Iran, Iraq, Azerbaijan) divided further into Imami (Twelver) Shi’ism, Isma’ili (Sevener) Shi’ism, Zaydi, etc., largely over differences in Imams. Each sect holds certain hadith collections and chains of transmission in higher esteem than others. For instance, many hadith that Sunnis accept are not recognized by Shi’as, and vice versa, because the Hadith transmitters often took sides in early disputes. This led to, effectively, “two hadith corpora with disparate content” in Islam – one Sunni, one Shi’a . As an insightful analysis on Islam’s sectarian hadith divide explains, “these individuals [narrators] were politically and theologically divided, [which] was reflected in [the] divide between the scholarship descending from them”. Thus, “there must have been people with sharply different understandings of Islam… [and] deep social fault lines very early in history that caused knowledge… to be funneled into two separate groups,” each developing its own hadith tradition . The very need to rely on such divergent reports implies that Islam, from its early decades, lacked a single cohesive interpretive authority, a stark contrast to its claim of unity under one Prophet and one Book.

Beyond Sunni and Shi’a, many other sects and movements have arisen in Islam. Some emerged in the very first centuries: the Kharijites, for example, broke away during the first civil war (656–661 AD), espousing an extremist view of piety and declaring other Muslims who commit grave sins to be apostates. The only surviving branch of Kharijites today are the Ibadis (in Oman and parts of Africa). Another early theological school, the Muʿtazilites, promoted a rationalist interpretation of Islam (denying the eternal nature of the Qur’an, affirming free will, etc.); they were eventually marginalized by Sunnis but influenced Shi’a thought. In more recent times, sects like the Ahmadiyya(founded in 19th-century India, claiming that Mirza Ghulam Ahmad was a kind of prophet/messiah) and the Nation of Islam (an American movement with highly unorthodox doctrines) have appeared – and mainstream Islam often considers these groups outside Islam altogether. Even within Sunni Islam, there are modernist vs. fundamentalistcurrents, Sufi mystical orders vs. puritanical Salafi groups, etc. The net result is that Islam is far from monolithic. As one survey of Islamic sects observes, “there are many different sects or denominations” in Islam, and “some of the Islamic sects and groups regard certain others as deviant or not being truly Muslim” . For example, Sunni authorities frequently do not recognize Ahmadis as Muslim, and often mistrust Alawites or heterodox groups; similarly, Shi’as historically were branded as heretics by Sunnis (and in some cases vice versa) . Tragically, this has led to not only theological disputation but also bouts of violent conflict between sects (the Iran–Iraq War, Sunni vs. Shi’a tensions in many countries, etc., echoing the old feuds).

This fragmentation within Islam underscores that the clarity of God’s revelation in Scripture is lacking in the Quran-Hadith complex. The Reformers believed that although Christians may have disagreements, the core doctrines necessary for salvation are clearly set forth in Scripture, which itself is perspicuous in essentials under the Holy Spirit’s illumination. Islam, claiming a clearer final revelation, nevertheless splintered early and often. Greg Bahnsen pointed out that any non-Christian worldview will have internal contradictions that lead to divisions, because without the true light of Scripture, human interpretations spin out myriad errors. In Islam’s case, “sharply different understandings” of faith appeared immediately after Muhammad, indicating a lack of a unifying principium beyond political force . The existence of separate hadith canons and legal schools suggests that Islam’s sources are not self-interpreting or self-authenticating in a way that secures unity of belief. By contrast, Reformed Christianity holds that Scripture interprets Scripture and that the gospel message is clear enough that, wherever the Bible is faithfully taught, the same core truths will emerge by God’s grace, a unity not imposed by sword or state but by the Spirit and truth.

It should be noted, of course, that Christianity too has many denominations and sects. A Muslim apologist might counter that this undermines Christian claims of clarity or truth. The Reformed response is that divisions in Christendom result when people depart from the clear teaching of Scripture (introducing tradition or human innovations, as in Roman Catholicism or various cults) – in other words, division is blamed on human sin and failure to adhere to Scripture alone. In Islam’s case, however, even those who ostensibly held only to the Qur’an and Muhammad’s teachings split deeply from the start, suggesting that the Islamic revelation itself lacks the internal consistency and perspicuity that would mark a truly divine communication. The English Puritans sometimes commented on Islam’s divisions as a judgment of God: just as God allowed confusion at Babel, He allowed the rise of sects like the Sunnis, Shi’ites, Kharijites, etc., to confound a false religion. Samuel Mather, a 17th-century Puritan writer, wrote that the success of “Mahometanism” was a scourge on apostate Christianity, yet its internal strife showed God’s hand against it. Bullinger had similarly remarked that Islam arose as a judgment on a corrupt church and that Muslims then fell into schism themselves, a cycle permitted by God for ultimate good.

Hadith Content Issues. In addition to sectarian divergence, the content of some hadiths raises theological and moral issues that Reformed critics highlight. For example, certain hadiths attribute questionable acts to Muhammad (such as marrying a very young Aisha, approving of the killing of apostates, etc.) or bizarre teachings (like the sun prostrating under God’s throne at sunset). These pose problems for Islam’s claim that Muhammad is the perfect example (al-insān al-kāmil) of conduct. The violent or unmerciful precedents in some hadith (e.g. prescribing stoning for adultery, or execution for those who leave Islam) contrast with the ethic of the New Testament. James White has noted that Islam’s doctrine of jihad and use of violence can be traced to its foundational texts, whereas the Christian faith from its beginning spread by preaching and service, not conquest . Some Puritans labeled Islam a “bloody religion” in contrast to the gospel of peace, though they also acknowledged many Muslims lived peaceably, attributing that to their inconsistency with the full rigor of Islam. This line of critique ventures into historical and ethical territory beyond pure theology, but it ties back to theology in that one’s concept of God and salvation deeply influences ethics. A works-oriented religion lacking assurance of salvation (like Islam) may foster either spiritual anxiety or militant zeal, whereas the Reformed faith, teaching salvation by grace, promotes grateful obedience and trust in God’s sovereignty. Indeed, one commentator in a Reformed review of James White’s book noted that “Islam is intrinsically violent, though most Muslims are not consistent with this”, pointing to an inherent tension between Muhammad’s militant example and many Muslims’ personal peacefulness .

Conclusion

In closing, a Reformed theological assessment finds Islam and the Qur’an fundamentally deficient in the most important matters of faith. Islam’s conception of God is profoundly inadequate – affirming divine unity but denying God’s Triune nature and the divine Son who alone reveals the Father. Its doctrine of revelation is self-refuting – claiming to honor prior prophets while contradicting their message, and asserting a perfectly preserved Qur’an belied by evidence of textual variant readings and human editing. Its view of Christ is gravely in error, honoring Him as a prophet but denying Him as Lord, Savior, and even crucified Redeemer, thus rejecting the only means by which God provided forgiveness of sins. Its scheme of salvation is hopelessly flawed – exhorting moral obedience and ritual without a sufficient atonement for sin, leaving the sinner without assurance and God’s justice unresolved. The multiple sects of Islam, each with divergent hadith and interpretations, further demonstrate the instability and “confusion” (to use Calvin’s term) inherent in a religion that broke from the solid foundation of Scripture to follow a new claimed revelation.

By contrast, the Reformed Christian faith offers a consistent, unified theology centered on the person and work of Jesus Christ, the incarnate Son of God. It proclaims what the Qur’an misses: that “God was in Christ reconciling the world to Himself” (2 Corinthians 5:19), that Jesus is Lord – not a mere prophet – and that through His death and resurrection, grace is freely given to sinners who believe. The Old and New Testaments form one harmonious revelation pointing to Christ; there is no need for a supposed further book to correct them, especially one that lacks the confirming marks of fulfilled prophecy and resurrection power. The Reformers saw Islam as a tragic falsehood: in the words of the Belgic Confession, it is among those religions that “damnable impostures” the devil has raised up to distort the truth (Belgic Confession, Art. 9, referring to “the Jews and the Muslims” who deny the Trinity). They earnestly prayed and worked for the conversion of Muslims – not out of hatred, but out of love, desiring that Muslims come to know the fullness of God’s revelation in Christ. The Gospel of Jesus answers the deepest longings that Islam cannot satisfy: assurance of salvation, a personal and covenantal relationship with God as Father, and a Savior who truly redeems from sin’s curse. The flaws of Islam’s theology thus serve to highlight by contrast the glory of the Christian gospel. As the Puritan missionary Henry Martyn (who served in Persian and Arab lands) once observed, Islam in denying Christ’s deity “has left mankind a system in which God’s mercy is eclipsed and His justice unsatisfied”, but in Jesus Christ, the justice and mercy of God meet perfectly at the cross.

Islam represents a zeal for God “not according to knowledge” (Romans 10:2). It contains echoes of truth, God’s oneness, the call to moral living, the witness of earlier prophets – but these are ultimately overshadowed by error: a rejection of God’s triune nature and saving grace, and a reliance on an insufficient revelation and human righteousness. Five centuries ago, the Protestant Reformers contended not only with Rome but also reflected on Islam, and their counsel still stands: the church’s response to Islam’s rise should be to hold fast to Scripture, to proclaim the biblical Gospel of Christ crucified and risen, and to pray for the conversion of Muslim souls. Islam’s theological flaws are exposed by the light of God’s Word , and it is our task as Christians to lovingly share that light. As the Westminster Confession (I.5) reminds us, the Scriptures manifest themselves to be from God by the “heavenliness of their matter” and “consent of all the parts” – qualities lacking in the Qur’an. We therefore conclude that the Qur’an is not the Word of God, and Islam’s theology, built upon it, is a house on sand. The sure foundation is Jesus Christ, the Son of God – “For no one can lay a foundation other than that which is laid” (1 Corinthians 3:11) – and any system that rejects Him, however fervent, is fundamentally flawed and unable to save. Our prayer is that Muslims and all others would come to know the truth as it is in Jesus, for “you will know the truth, and the truth will set you free” (John 8:32).

1. James R. White on Islam’s Misunderstanding of the Trinity: Christian Post interview with James White (2013), noting “the writer of the Qur’an [did not understand] what the doctrine of the Trinity was,” as the Qur’an wrongly identifies the Trinity as Allah, Mary, and Jesus . White explains the Qur’an’s only reference to a triad (Q 5:116) implies “God had a wife and a kid named Jesus,” a glaring misrepresentation of Christian doctrine .

2. Veritas Domain – Review of White’s Book: Review of What Every Christian Needs to Know about the Qur’an, mentioning that Dr. White “demonstrates – admirably – the ‘flaws’ in Islamic theology. For example, its misunderstanding of the Trinity and the incarnation.” . This highlights White’s identification of key doctrinal errors in Islam.

3. Ligonier Ministries (Reformation Perspective on Islam): How Did the Reformers View Islam? – Article summarizing Reformation-era assessments of Islam . It explains that Reformers saw Islam as a Christian heresy, rejecting the Trinity and Incarnation (like Arianism) and teaching works-salvation (Pelagianism) . John Calvin is quoted regarding Islam not remaining “enclosed within Holy Scripture” by adding new revelation . Also notes Bullinger’s view of Islam as God’s judgment and Calvin’s exhortation to hold to pure religion against such “defections” .

4. Westminster Confession of Faith I.6 (1646): The Confession asserts Scripture’s sufficiency: “The whole counsel of God…either expressly set down in Scripture or by good and necessary consequence deduced…unto which nothing at any time is to be added, whether by new revelations of the Spirit or traditions of men.” . This doctrinal standard of the English Puritans implicitly refutes the Qur’an’s claim to be a later revelation supplementing Scripture.

5. Biblical Warning Against False Revelation – Galatians 1:8: “But even if we or an angel from heaven should preach…a gospel contrary to the one we preached to you, let him be accursed.” . This apostolic warning is often applied to Muhammad’s claim of angelic revelation bringing a new gospel, thus highlighting Islam’s incompatibility with the New Testament message.

6. 1 John 2:22–23 on Denial of Christ: “This is the antichrist, he who denies the Father and the Son” . The Scripture clearly brands as antichrist any religion (like Islam) that denies Jesus is the Son of God, underlining the severity of Islam’s error from a Christian standpoint.

7. Bahnsen’s Presuppositional Critique of Islam: Greg L. Bahnsen, Presuppositional Reasoning with False Faiths (Bahnsen Institute, 2023) – Bahnsen shows internal inconsistencies in Islam . He notes the Qur’an “acknowledges Moses, David, and Jesus” as prophets but then contradicts their teachings, refuting itself on its own terms . He also argues that Islam’s view of salvation (no substitutionary atonement) fails to satisfy God’s justice: “The legalism of Islam (good works vs. bad) does not address [the] problem [of unforgiven guilt]… previous bad works…continue on one’s record in the sight of Allah (who supposedly cannot tolerate sin but must punish it).” .

8. Keith E. Small on Qur’anic Textual History: Textual Criticism and Qur’ān Manuscripts (2011) summary . Small concludes “there never was one original text of the Qur’an” and that the ʿUthmanic project “eliminated many texts” with authentic readings. He notes prior to standardization there were “50 different ways” of reciting the Qur’an, indicating significant early textual variation .

9. Sahih al-Bukhari Hadith on ʿUthman’s Compilation: Sahih Bukhari 6:61 #510 (4987) – Narrated by Anas: ʿUthman feared differences in Qur’an recitation and “sent to every Muslim province one copy of [the compiled text], and ordered that all the other Qur’anic materials…be burnt.” . This authentic hadith documents the deliberate elimination of variant codices, demonstrating that the Qur’an’s text underwent an editing process to ensure uniformity.

10. Hadith of the “Lost” Stoning Verse: Account from Sunan Ibn Majah (hadith no. 1944) as cited in Islam Q&A: “The verse of stoning and breastfeeding an adult ten times was revealed, and it was written on a leaf… When the Messenger of Allah died, we were preoccupied with his death, and a tame sheep came in and ate it.” . Although judged weak, this narration (from ʿA’ishah) is frequently noted to suggest that some revealed texts never made it into the Qur’an due to mishap, raising questions about perfect preservation.

11. Islamic Sects and Schools (Wikipedia): “Islamic schools and branches” overview . It states Sunnis comprise 87–90% of Muslims, with Shi’as, Kharijites (Ibadis), etc. making up the rest . It also notes, “Some of the Islamic sects and groups regard certain others as deviant or not truly Muslim (for example, Sunnis frequently discriminate against Ahmadiyya, Alawites, Quranists, and sometimes Shi’as)” . This underscores the internecine disunity in Islam.

12. Sunni vs. Shi’a Hadith Divide (Islam StackExchange): Explanation that the divergence in hadith collections was due to early political-theological splits. “All of this has led to formation of two hadith corpora with disparate content… implying… sharply different understandings of Islam… and deep social fault lines very early in history….” . One Islam developed under the Sunni ruling majority, the other under the Shi’a minority; their source materials seldom overlap, reflecting and reinforcing sectarian theology .

13. Christian Post – James White on Qur’an’s View of Christianity: Myles Collier, “What the Qur’an Gets Wrong About Christians”, The Christian Post (May 2, 2013) . White explains that the Qur’an’s only engagement with Christian doctrine mistakenly assumes tritheism (with Mary as a goddess), showing no awareness of the true Trinity. This misapprehension leads the Qur’an to attack a “straw-man” version of Christian belief. White concludes the author of the Qur’an “didn’t understand” the Trinity, a serious theological flaw .

14. Reformation21 (Scott Oliphint) – Sufficiency of Scripture: Commentary on WCF 1.6 . Emphasizes that we need no “extra” word beyond Scripture for salvation and godliness. Islam’s insistence on the necessity of the Qur’an and Hadith as additional revelation directly contradicts this principle, placing Islamic doctrine outside the bounds of what Reformed Christianity considers legitimate revelation .

15. Bahnsen, “The Crescent or the Crown” (Debate): (Referenced in Bahnsen’s footnotes ) – Bahnsen’s 1991 debate “Sister Faiths? Islam and Christianity” and lecture “The Crown or Crescent” examine Islam’s internal problems, such as its extreme transcendence doctrine (Allah so removed that positive attributes become unknowable, undermining the Qur’an’s own claims) and the unresolved tension of divine justice vs. mercy in the absence of the cross . These resources reinforce how Reformed apologetics highlight Islam’s worldview incoherence while presenting the coherence of the biblical worldview.

All glory be to God Triune – Father, Son, and Holy Spirit – “the only true God, and Jesus Christ whom [He has] sent”(John 17:3), apart from whom no religion can lead to the truth. Soli Deo Gloria.