I used to think I was an atheist, but I realized I'm an adeist. I can't be sure of the ultimate nature of reality, nobody can really, I just know I want to explore what reality is and find all the answers I can. But when it comes to some separate conscious "guy" up there, creating the universe, judging our actions, punishing and rewarding us according to how we stroke his ego and follow his rules... well that's just an incredibly primitive notion IMO.