In logic, one cannot prove a negative. A small minority of atheists have offered proof of nonexistence, but even to me, the "proof" is unconvincing. Most atheists won't offer proof for or against, because they understand such proof does not exist. Atheists simply don't have a belief in a god, and the burden of proof always lies with the person making the claim. For most atheists I have met, where a theist has a belief, the atheist just as an empty parking place, waiting for something, possibly something even profound, to fill it. One friend explained the position this way: Without proof either way, the issue of god's existence is irrelevant. That hit me pretty hard, but I think that would be logically appropriate for an atheist.