Jesus never claimed to be God. The idea was invented later — you can watch it grow from Mark to John, and it was finally voted into doctrine at Nicaea.

Why people find it persuasive

The observation behind the objection is accurate as far as it goes. Jesus nowhere in the Synoptic Gospels says the sentence 'I am God,' and the vocabulary of the Nicene Creed — homoousios, one substance, two natures — is fourth-century philosophical language he never used. Bart Ehrman's How Jesus Became God argues at book length that a Galilean preacher was progressively exalted by his followers, and to anyone reading Mark and then John back to back the difference in register is unmistakable.

Important distinctions

• • Explicit self-designation ('I am God') vs. implicit claim through action, prerogative, and scriptural allusion.
• • Fourth-century creedal vocabulary vs. first-century Jewish idiom for divine identity.
• • Development of language and category vs. invention of the underlying claim.
• • What Jesus is reported to have said vs. what his earliest followers already believed about him.

Christian response

• • Start by asking what a first-century Jew would actually have said if he wanted to claim divine identity, because 'I am the second person of the Trinity' was not available vocabulary. Within Second Temple Judaism, divine identity was marked by function and prerogative: who creates, who rules, who forgives, who receives worship. Richard Bauckham's work on 'divine identity Christology' makes the case that the New Testament writers include Jesus within the unique identity of the God of Israel using precisely these Jewish categories rather than later Greek ones — which is exactly what we should expect if the claim is early and Jewish rather than late and Hellenistic.
• • Now look at what the Synoptics actually have Jesus doing. He forgives sins directly, not as a priest pronouncing forgiveness but on his own authority, and his hearers immediately grasp the implication (Mark 2:5-7). He declares himself lord of the Sabbath, an institution grounded in God's own creative rest. He performs a symbolic action of judgment on the Temple, the place of God's presence. He calls twelve, reconstituting Israel around himself. None of these is a creedal sentence; all of them are claims that a merely prophetic figure had no standing to make.
• • The Son of Man language cuts against the objection rather than for it. Popular treatments read 'Son of Man' as a humility title, but its background is Daniel 7:13-14, where one like a son of man comes on the clouds and receives everlasting dominion and the worship of all peoples. When Jesus applies that text to himself before the Sanhedrin in Mark 14:62, the high priest's reaction is not confusion but a charge of blasphemy — which tells us how the claim was heard by hostile listeners in the moment.
• • The decisive evidence is chronological. Larry Hurtado's Lord Jesus Christ documents devotional practice — prayer to Jesus, invocation, hymns, baptism in his name, the Aramaic prayer maranatha preserved untranslated in 1 Corinthians 16:22 — within the first two decades among monotheistic Jews. Pre-Pauline material embedded in Paul's letters points the same way: the hymn of Philippians 2:6-11 applies Isaiah 45:23, a text about YHWH alone, to Jesus, and 1 Corinthians 8:6 splits the Shema itself so that Jesus occupies the 'one Lord' clause. Paul is quoting formulas already in circulation, which puts a very high Christology within a handful of years of the crucifixion, not centuries.
• • That leaves Nicaea, and here the historical record is simply clear. Nicaea in 325 did not invent Christ's divinity; it adjudicated between two parties who both already worshipped him, and it defined the vocabulary in which the long-held claim would be stated. The Arian position was not that Jesus was merely a man but that he was a created heavenly being. Whatever one concludes about the outcome, the council's minutes are not the birth certificate of the doctrine, and pretending otherwise misdates the debate by nearly three hundred years.

Christian counterresponse

The Christian reply is that the post-Easter account has to explain why these particular monotheists reorganized their worship around a crucified man at all, when messianic movements whose leader was executed uniformly dissolved or found a new leader. It also has to explain why the implicit claims in the earliest stratum, Mark included, run in the same direction as the later explicit ones. Dale Allison, who is not making an apologetic case, argues that Jesus plausibly held an extraordinarily elevated view of his own role.