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.
I think the difference between doubting Pythagoras and doubting Jesus is that no one is claiming g Pythagoras existed to bolster their claims on holding a moral superiority. A lot of historical research (especially early on) into the history of Jesus is done by religious scholars who are explicitly seeking to back up things they already believe. I don’t trust them. Most of the consensus is built upon this pre-conceived idea that he’s real, and so the support is on shaky footing.
No one really cares if Pythagoras existed or not, so it’s not worth considering. A lot of people hold a certain (potentially harmful, or at least ignorant of reality) view on the world because of a supposed figure named Jesus, and the fact there isn’t much evidence he existed at all pretty heavily breaks the illusion we know he did miraculous stuff. If it’s questionable that he even existed then it’s certainly questionable that he did anything special.
The fact is, historical consensus is built on backing up a belief, in this case. Not on fact originally. It becomes incredibly hard and dangerous to your career to question the consensus without evidence —and you can’t have evidence of non-existence. That means anytime anyone questions it people yell “most historians agree!” and no further questions are asked. I think it’s much healthier to question it, regardless of what the consensus is. It wouldn’t be the first time it’s been wrong, and it can’t hurt to be skeptical.