I think Lemmy has a problem with history in general, since most people on here have degrees/training in STEM. I see a lot of inaccurate “pop history” shared on here, and a lack of understanding of historiography/how historians analyze primary sources.
The rejection of Jesus’s historicity seems to be accepting C S Lewis’s argument - that if he existed, he was a “lunatic, liar, or lord,” instead of realizing that there was nothing unusual about a messianic Jewish troublemaker in Judea during the early Roman Empire.
The earliest Gospel, Mark, was written about 70 CE. (There’s also evidence that a “Q source” and a “sayings source” were floating around earlier - the commonalities in Luke and Matthew) Paul’s epistles are even earlier; Galatians was written somewhere 40-60 CE. Paul’s epistles are written to communities of Christians, meaning that that Christianity has already spread by then.
It’s not quite certain that Jesus and Paul actually met in person. So all his writing might be apocryphal. His word might have become christian canon, but he is not really a source one can trust.