I do not believe atheism is synonymous with nihilism. For instance, if I am an atheist, but I have a rich values-system indeed, consisting of democratic egalitarianism, I do count myself as a nihilist, even though a subclass of atheists may indeed be nihilists.

Incidentally, I wonder how you reconcile your strong appreciation for post-modernism while apparently disdaining nihilism. It seems to me that there is a closer association between nihilism and post-modernism that between nihilism and atheism, as post-modernism seems to be pretty valueless. I wonder that we should vote for a post-modernist!