I would never forget the moment I became an atheist - it was somewhere in the middle of the 7th grade, and we had a lesson about the emerging empires in Mesopotamia ( The first time history touches organized religion, at least in my school). I was cautiously believing in christ then. Anyway we were discussing the merits of their religion (sovereign chosen by god, underworld or something like that), and it was all clear that their notion of religion was silly and could never be true, yet they passionately believed it. On top of that it was obvious that the ruling class had invented it to serve it's needs (the sovereign was entitled to his position, so was his family and hairs). And then it struck me, what will be different in say 3-4 thousand years into the future, when in some class a child will be learning about christianity, and discussing it's merits. In that exact moment the whole pillar of belief (which my parents were relentlessly building) crumbled like the WTC.

Anyway, that's my 2 cents.