I think there's a negative, antireligious tone to the term "Atheism." If atheisim exists simply to deny the beliefs of those are religious, then it is a creed that essentially negative and destructive in nature. I don't think the atheists I know are like that - they're very positive, good people who just don't believe in God. They tolerate my religious beliefs quite well, and they share many ethical views with me. The idea of "secular humanism" and the practices of the ethical societies seem to typify the atheists I know.
A couple types of music that might fit the description of "humanist" music are the union and civil rights songs that were fashioned from old-time gospel songs. We had quite a discussion of those songs in this thread (click).
-Joe Offer-