Kravenhead #fundie answerbag.com
People can become an atheist for many reasons. It could be a result of anger, frustration, resentment etc. due to some unpleasant experience, relating to a church or religion (although its not likely you'll get an atheist to admit it). Another could be the individual's inability to rationalize the concept of God. We all have a tough time with that, even the clergy have difficulty with the logic. I don't think we can reasonably fault, any person for that, because I don't believe anyone can fathom infinaty or omnipotence and omniscience, we just can't corral those concepts in our minds, so we can see them clearly. The belief in God, in my opinion, is reliant upon reasonable probabilities and faith, not the rationalization of impossibly imagined concepts. Many atheists are just trying to be rational, with out applying the unknowns to the equation.
[Dear god: if you really exist, please, give me one sign by making irony and stupidity hurt. Ahmen!]