Ramesh Ponnuru asks an interesting question:

…what’s the best term to refer both to agnostics and atheists? “Faithless” seems too negative, “bright” too propagandistic. Do agnostics and atheists consider “unbeliever” better than “non-believer,” or vice-versa? When I was agnostic, I didn’t take my own unbelief seriously enough to consider this question.

I’ve never given much thought to the matter, but if one insists on lumping both into the same category, I’d say that “non-theists” seems both accurate and non-pejorative (other than to those to whom not believing in God is an intrinsically bad thing…).

But I think that the distinction between atheists and skeptics is important. The former (based on my experience with them) are as devout, or (actually) more devout, than most theists. They fervently believe (unprovably) that there is no God, and will proselytize endlessly to convert others to their belief. I have no belief, one way or the other, and it would never occur to me to (futilely) attempt to persuade a believer, of either faith, one way or the other.