I think some of the best points of this thread, points that deal with the initial question, are being buried by attempts to define a term that is, as someone stated earlier in the thread, arbitrary.
One of the definitions of god could be a natural human response to the cold harsh world it lives in, an attempt to indentify with that world, and create a bond with it, or humanize it (put a face to it, god). Then instead of a harsh unforgiving world where life means nothing, and your value as an individule is rewarded only with death, the uncaring reality around you suddenly has a kind face that gives you a purpose and a promise of some type of reward. The pitfall is that instead of seeing reality you only see illusion, and in that illusion there are many unrealistic paths which you can see people walking in todays society.
Atheism also has pitfalls, a supposed realization that there is no god often comes hand in hand with a belief that there is no order, or no point to anything. It's possible to be an atheist, and still contribute positive things to the human species, just like it's possible to do the same as a religious person. I don't see as much of a problem with being an atheist, but you just have to be careful to realize that just because there is no one looking over your shoulder, you still have to realize that there is still a purpose, the furthering and bettering of our species.
To me, the pursuit of reality relative to the quality of human kind, without the promise of reward, but simply because it's what needs to be done is more 'noble' than anything. Nihlism as defined on this site, and the works they promote, is the best means to this end. Atheism is a potential detractor, I think that is the answer you are looking for.
*edit* My definition of god, arbitrary as the term is, came from Freud's 'The Future of an Illusion'. Well worth the read.