When I was 13 years old I figured out that people of other faiths believe in their Gods just as fervently as my devout and conservative family believed in theirs.

Since truth isn't determined by where you happen to be born, it seemed unlikely that my family's God was the one true God while all the others were false.

That's the "aha" moment that changed the course of my life.

Well, that and learning Bayes' theorem.