According to militant atheist Keith Parsons:
Let’s try a thought experiment: What would a contemporary account of Jesus have looked like had it been written by a historian with the resources, aims, and methods of a modern critical historian?… Now, of course we do not know what our imaginary historian would have concluded, but it should be abundantly clear that his product would be very different from the Gospel records.
Of course, that’s a wholly artificial comparison. We don’t measure ancient historians like Julius Caesar or Dio Cassius by that anachronistic yardstick. Ancient history will be written according to period conventions.
So let’s try a different thought experiment. Imagine that you’re an atheist. But suppose, for the sake of argument, that Jesus really was the Son of God Incarnate. Suppose he really did live and die in 1C Palestine, perform miracles, rise from the dead, and return to heaven.
Suppose four biographies were written about him. Suppose one was written by a Jewish disciple and a member of his inner circle (John). Suppose one was written by another Jewish disciple (Matthew). Suppose one was written by a younger contemporary who was a native of Jerusalem (Mark). Suppose one was written by a gentile Godfearer who had extensive contacts with members of the 1C church (Luke).
How would we expect these ancient biographies to differ, if at all, from the canonical gospels? Wouldn’t we expect their biographies to reflect the literary conventions of Biblical and Hellenistic historiography? Wouldn’t we expect them to link the life and ministry of Christ to OT prophecies? Wouldn’t we expect them to adapt their presentation to their target audience? Wouldn’t we expect them to reflect differences in their individual background and personal experience? Wouldn’t we expect them to record miracles of Christ? Wouldn’t we expect them to alternate between a chronological presentation and a topical presentation? In sum, what would be different if it were true under the circumstances?