"Given that Jesus was supposedly a very noteworthy figure who died in a noteworthy way founding a major religion, the total absence of any historical record of him or anyone substantially resembling him would be very surprising if he was real."
What would you accept as evidence? Seriously.
What would you accept as evidence? Seriously.
Documentary evidence that dates from the time of Jesus' supposed life and death, which describes a religious leader called Jesus who started a splinter sect of Judaism would do it.
I wouldn't be in any way upset if such evidence emerged tomorrow, but I think it's very unlikely. Pious researchers have been looking very hard for a very long time for even a shred of contemporary evidence for a historical Jesus that isn't forged, and they've come up with nothing so far. When people have looked long and hard for evidence and found none the probability that there is no evidence to find gets very high.
To break up the awkward silence at the start of a recent Overcoming Bias meetup, I asked everyone present to tell their rationalist origin story - a key event or fact that played a role in their first beginning to aspire to rationality. This worked surprisingly well (and I would recommend it for future meetups).
I think I've already told enough of my own origin story on Overcoming Bias: how I was digging in my parents' yard as a kid and found a tarnished silver amulet inscribed with Bayes's Theorem, and how I wore it to bed that night and dreamed of a woman in white, holding an ancient leather-bound book called Judgment Under Uncertainty: Heuristics and Biases (eds. D. Kahneman, P. Slovic, and A. Tversky, 1982)... but there's no need to go into that again.
So, seriously... how did you originally go down that road?
Added: For some odd reason, many of the commenters here seem to have had a single experience in common - namely, at some point, encountering Overcoming Bias... But I'm especially interested in what it takes to get the transition started - crossing the first divide. This would be very valuable knowledge if it can be generalized. If that did happen at OB, please try to specify what was the crucial "Aha!" insight (down to the specific post if possible).