I am an atheist because I have never seen any real evidence of any gods of any kind. I was raised Catholic and later converted to Baptist as an adult. Even as a child it bothered me that god did not act in obvious and public ways as depicted in the Bible. The liberal interpretation that the supernatural events in the Bible should be interpreted metaphorically only begged the question why the god entity shouldn’t be interpreted metaphorically as well. Also, as an African American I can’t reconcile accepting a religion that was used to enslave my ancestors.
But seeing George Carlin’s routine Religion is Bullshit sealed my atheism.
(I put out a simple call for your explanations for why you’re an atheist, and I’m still inundated with submissions. This will be a daily feature on Pharyngula.)