Doubt. Similar to the doubt that drove me away from Christianity. Atheist like to call out "the man with a beard in the sky!" And I think it's clear that the perceived image of a god is one that helped people relate to it. I'd say the chances of the literally interpreted god being real are about as close to absolute zero as you can get. But the universe is a weird place, and the idea that there is something out there that sort of ties it all together, not a deity with a face but something our brains cannot fully comprehend, is not out of the realm of possibilities for me. I'm not saying I believe it with all of my heart, but there is a doubt in my mind that it's all just nothing. Edit: Wow, this got a lot more responses than I expected. I'd love to sit down and reply to all of them as most of them are very reasonable replies with questions or arguments. But I can't. Firstly, I do not think an atheistic (as I define it, no god, no afterlife, just completely lack of existence beyond life and ultimate death) universe is meaningless or "nothingness" as it might have come off. I find great solace in the idea that our actions can ultimately ripple through time so long as there is a human race to carry on the reaction of our causes. It gives reason to be a kind person, and to stand up for justice and a betterment of all mankind. If that isn't a meaning to life, then I do not know what is. And to go along with the previous statement. I am not all tied up with what the definitions are for belief. For me, Atheism was the belief that there is no "higher power" that exists beyond the plains of science as we know it, and that belief is final, no room for speculation. In this sense I define my belief as agnostic, though there are many times where I think there must be something more. This belief could extend from all sorts of things, from fear of death or to inability to accept that random chance is the causation of many things in my life and that I will only ever get to experience the one life, the one series of events that will ultimately make up my life. In the end, everything will seem like fate because I will only see one way of things.