Behind every doctrinal disagreement between Christianity and Islam stands a prior question: which book tells the truth, and on what basis? Islam teaches that the Qur'an confirms the earlier scriptures while correcting and superseding them, and that the Bible Christians hold today has been altered from what Allah originally revealed. Christianity teaches that Scripture is a single, progressively unfolding revelation that culminates in Christ and requires no later correction. This installment examines both claims against each other and against the manuscript evidence.

What Islam Teaches: The Qur'an as Final, Superseding Revelation

Islam teaches that Allah has sent revealed books to various prophets across history — the Torah (Tawrat) to Moses, the Psalms (Zabur) to David, and the Gospel (Injil) to Jesus — and that the Qur'an, revealed to Muhammad, is Allah's final and complete revelation, which "confirms" the earlier books while also correcting and superseding them:

"It is He who has sent down to you, [O Muhammad], the Book in truth, confirming what was before it. And He revealed the Torah and the Gospel. Before, as guidance for the people." — Qur'an 3:3–4

"And [recall] when Jesus, the son of Mary, said, 'O children of Israel, indeed I am the messenger of Allah to you confirming what came before me of the Torah and bringing good tidings of a messenger to come after me, whose name is Ahmad.'" — Qur'an 61:6

A significant complication arises within the Qur'an's own statements about the Injil (Gospel), worth noting honestly because it is a matter of internal textual coherence rather than an outside polemical point: the Qur'an describes the Injil as a book given to Jesus by Allah ("We gave him the Injil, in which was guidance and light," Qur'an 5:46; cf. 19:30, where Jesus says as an infant, "God has given me the Book") — parallel to how the Qur'an itself was, in Islamic belief, dictated to Muhammad. Yet the New Testament — the actual "Gospel" (from Greek euangelion, "good news") held by Christians as their Scripture — never claims to be a book dictated to Jesus. It consists of writings composed by Jesus' apostles and their associates (Matthew, Mark, Luke, John, and the rest of the New Testament) about Jesus' life, death, and resurrection, written in the decades following his ascension. The Qur'an also identifies the Injil explicitly as the very Scripture Christians already possess in their own hands: "let the People of the Injil judge by what Allah has revealed therein" (Qur'an 5:47); "O People of the Scripture, you are [standing] on nothing until you uphold the Torah, the Gospel, and what has been revealed to you from your Lord" (Qur'an 5:68). These two claims — that the Injil is a book dictated to Jesus, and that the Injil is the Scripture already held by Christians — describe two different kinds of documents, and the New Testament that Christians actually possess fits the second description (writings by and about Jesus' followers) but not the first (a book given to Jesus himself).

Because the New Testament so plainly does not read as a "book given to Jesus" and yet plainly disagrees with the Qur'an on matters such as the crucifixion and the divine sonship of Christ, many Muslims resolve the tension by appeal to tahrif — the claim that Jews and Christians corrupted or altered their scriptures. It is worth stating fairly, however, that the Qur'an's own textual support for a claim of deliberate textual corruption of the Christian New Testament specifically (as opposed to charges of concealment or misinterpretation, which are leveled mainly at the Jews regarding the Torah, e.g. Qur'an 2:75; 4:46; 5:13) is thinner than popular usage assumes; many scholars of Islam, both Muslim and non-Muslim, note that classical exegetes were divided on whether tahrif meant a change to the wording of the text itself (tahrif al-lafz) or merely to its interpretation and application (tahrif al-ma'na).

What Christianity Teaches: A Coherent, Preserved, Christ-Centered Canon

Scripture presents itself as a single, unified, progressively unfolding revelation that culminates in Christ rather than needing correction by a later book. Paul writes to Timothy that "all Scripture is inspired by God and profitable for teaching, for reproof, for correction, for training in righteousness" (2 Timothy 3:16) — the Greek θεόπνευστος (theopneustos, "God-breathed," BDAG 452) describes the entire Old Testament (the Scripture Timothy had known "from childhood," 2 Timothy 3:15) as the direct product of God's own breath, not merely human religious reflection later touched by revelation.

The New Testament claims that Jesus himself is the substance to which the entire Old Testament points: "You search the Scriptures because you think that in them you have eternal life; it is these that testify about Me" (John 5:39); on the road to Emmaus, the risen Christ, "beginning with Moses and with all the prophets, He explained to them the things concerning Himself in all the Scriptures" (Luke 24:27). Hebrews opens by describing revelation as a single, developing story: "God, after He spoke long ago to the fathers in the prophets in many portions and in many ways, in these last days has spoken to us in His Son" (Hebrews 1:1–2) — not a series of competing, mutually correcting books, but one story reaching its intended climax in the incarnate Son, after which Scripture nowhere anticipates a further, superseding prophet or book.

On manuscript grounds, the claim that the New Testament text was so thoroughly corrupted that its core teaching about Christ's deity and crucifixion cannot be trusted faces a substantial evidentiary obstacle: the New Testament is, by a wide margin, the best-attested body of literature from the ancient world, with over 5,800 Greek manuscripts, plus tens of thousands more in Latin, Coptic, Syriac, and other ancient versions, some fragments (such as P52, a fragment of John's Gospel) dating to within a few decades of the autograph. Textual variants among these manuscripts are overwhelmingly minor (spelling, word order, obvious scribal slips), and no textual variant anywhere in the manuscript tradition removes or reverses the New Testament's teaching on the deity of Christ or his crucifixion — the doctrines a corruption theory would need to explain away. As the New Testament scholar F.F. Bruce observed regarding the manuscript evidence more broadly, no classical historical work from antiquity is remotely as well attested. Yet, no historian doubts the substantial reliability of, say, Julius Caesar's Gallic Wars, of which only a handful of late manuscripts survive (see Bruce, The New Testament Documents: Are They Reliable?, summarizing the comparative manuscript evidence). John A.T. Robinson's Redating the New Testament argues on internal and external grounds for dating the entire New Testament corpus before AD 70, decades closer to the events it describes than critics have often assumed (Robinson, Redating the New Testament, SCM Press, 1976).

The claim that "the Bible is corrupted," even when offered honestly as an explanation for disagreements with the Qur'an, therefore runs into a second and independent problem beyond the manuscript evidence: the timing does not fit. The Qur'an's own statements treating the Injil as a currently existing, authoritative scripture in the hands of Christians (Qur'an 5:47, 68) were revealed in the seventh century AD — centuries after the New Testament documents were written, copied widely across the Mediterranean world in Greek, Latin, Coptic, and Syriac, and dispersed among mutually independent and often theologically hostile church communities (Nicene, Arian, Nestorian, Monophysite, and others). For a deliberate, wholesale doctrinal corruption of the text — inserting the deity of Christ and the crucifixion where they did not originally appear — to succeed by the seventh century, it would have had to be executed in near-total secrecy and near-total success across all of these mutually suspicious factions simultaneously, with no surviving trace in any manuscript tradition, no historical record of the change, and no protest from any of the many groups (including groups Nicene Christianity regarded as heretical, who had every doctrinal motive to preserve a different text if one existed) who copied and preserved these texts independently across three continents. The manuscript record does not show this happening; it shows remarkable stability in the text's core content across every geographic and denominational line of transmission.