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).
There were quite a few troublemaking preachers who fell afoul of the law in Judaea at the time, many of whom were called Jesus - it was a very common name at the time.
However, one of the big problems with assuming one of these fellows (or another we have no documentation of) was the human seed for Christianity is the early Christian tradition of docetism - that Christ had no corporeal existence at all, and was just an idea. Paul of Tarsus certainly seems to think along these lines, despite the later caution against said notion in John.
This also helps explain the curious lack of non-Biblical evidence for such a person, in histories where one would expect it.
It is often noted by apologists that scholars think there's enough evidence to say there was a human seed for Christianity. However, "scholar" in this context is a weasel word - most are Christians and theologians, who would have tremendous trouble (personal and professional) coming to the opposite conclusion at all. The epistemological standards accepted in Biblical history in particular are generally bloody awful and an embarrassment to other ancient historians.
For a pile of stuff on this issue I recommend the RationalWiki article, which I have worked extensively on. (One of the other main contributors just so happens to be an atheist who was a student of Biblical history.)
(I find this stuff fascinating, if only for the psychopathology. And, as such strident atheists as Mencken, Dawkins and Hitchens have noted, you can't be highly literate in English without knowing the KJV, much as you need to know Shakespeare and Greek mythology. The trouble is that ... well, it's like you wanted to study the Odyssey or the Iliad but the only people to learn from were people who (a) actually believed in all the gods named therein (b) really wanted you to as well.)
(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.