Since it was asked for, I can provide the brief story of how I became an atheist. I absolutely am not trying to debate atheism vs. theism or looking to convert. Hopefully this just helps spread a little bit of understanding.
I was raised as a Catholic in a very Catholic family. My dad became a deacon when I was around 11 and has the equivalent of a degree in theology. Very smart guy. Always went to mass, always talked about the importance of jesus, etc. I was very into it all throughout my teen years. I even went on a bunch of teen retreats and ending up leading several retreats. I was very much a fervent teen Catholic. Looking back, I'm sure that my influence, witnessing, and enthusiasm for Catholic Christianity converted many teens.
When I went to college, I began to struggle with my faith. It began with small things, such as political stances all the christians around me seemed to be taking, and what I thought were ridiculous attacks on science. After that, all kinds of questions popped up. I began to question the philosophy of religion, and what I really 'knew'. The main problem for me was this: 'I've been raised Catholic and strongly believe in the Catholic god... but I also know that if I was born in Pakistan i would undoubtedly be a devout Muslim. How do I know which religion is real?'
I stopped going to church very often. I still wrestled with that one question of 'How can one determine which religion out of dozens (or hundreds) has the truth?' To me, there was no satisfactory answer. I gradually began to think of myself as a deist, who still believed in some sort of omniscient god but who didn't claim to know which form he took. I was firmly no longer 'religious' at that point. Gradually, belief in a god at all began to make less sense to me as well, and I simply dropped it. I consider myself an agnostic atheist, meaning that I don't deny the possibility of god outright but I also think it's pretty unlikely any gods exist.
That's pretty much it. I imagine it's fairly typical of the "lose your religion in college" story. I still know a good bit about the bible from my religious days, and still go to mass occassionally. I don't take communion, but it doesn't really bother me to go on special occassions like xmas, easter, etc.