(Restricting myself to two quibbles, for the sake of time):
I believe your description of Docetism gives the wrong idea; Docetism (as I learned it) did not say that Jesus was not there at all, but rather merely asserted that his corporeality was an illusion. The Docetists did not think of Jesus as "only an idea", but as somebody who staged a form of divine theater, as it were. (Research "Christological Heresies" for more on Docetism and its cousins.)
Quibble #2: not all biblical scholarship is as bad as you say -- much of it is quite rigorous and would be right at home in a secular university anthropology department.
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).