How would we know if Jesus was an actual figure of antiquity? How could we test the historicity?
We'd look for consistent, plausible accounts. We'd look for multiple records of existence from the time. We'd look for events ascribed to him being corroborated by other sources. There are none of these things.
Well, I would say that you first have to give the benefit of the doubt-- reason being, if you challenge the historicity of Jesus, arguably the MOST prolific figure in all of human history, you would also have to consider most other figures of antiquity to be little more than fantasy.
Where do Christians get this crap? The historical evidence for Jesus is scanty at best. You've got four gospels, most of which are partially derived from each other, or a fourth source and all of which were written decades after the event -
a timescale plenty long enough to allow mythology to develop. That's it. There's more justification for the existence of King Arthur and Robin Hood.
Why is it that the assumption of someone being an actual person is believed, even on scant evidence, where Jesus is immediately met with hostility? Perhaps its because of the claims He made.
Because the claims made about Jesus are extraordinary, and thus require extraordinary evidence.