Philosopher Stephen Law recently offered a novel reason for doubting the historicity of Jesus:
If two friends tell me that a man called Bert visited them at home last night, I have every reason to believe them. That’s evidence enough.
But if they then tell me that Bert flew around the room, then dropped dead, and them came back to life again, before turning the sofa into a donkey, well then that’s no longer nearly good enough evidence that they are telling the truth, is it?
In fact, not only am I justified in rejecting their testimony about the miracles, I would now also be wise to suspend judgement on whether any such person as Bert even exists, let alone did the things they claim.
In other words, even if one were to concede that the gospels were written by eyewitnesses (and Law does not concede this), the very fact that the gospels attribute miracles to Jesus reduces the probability that Jesus himself actually existed.
Law’s full discussion can be read here: http://stephenlaw.blogspot.com/2008/08/to-deny-that-jesus-was-solid-historical.html