Atheism, or Humanism?

It's almost summer reading program time! (What? You want to give me cool things for reading books?! I'm there!) I spent a couple summers post-graduate school catching up on all the good fiction I had missed during my academic seclusion. Then I was ready for topic-oriented reading again.

Now I'm torn as to how I want to spend this summer. For awhile I thought I'd take it easy and spend the summer upping my percentage on the cult fiction list. But recently I've had another thought... Humanist philosophy. I don't call myself a 'humanist' simply because I'm not well-versed in writings in humanism. But it seems to me that what I have read resonates with what I believe.

"Humanism entails a commitment to the search for truth and morality through human means in support of human interests."

Perhaps why I can like humanism so much is that it is not defined at the expense of something else. Atheism, by definition, is simply the denial of something else. If you say you are an atheist, you are essentially only saying that you are not part of a group that believes in a god. You are defining yourself in relation to another belief system that you disagree with. In effect, you are still defined by that thing which you reject. If that is all that defines you, then affirming yourself involves attacking someone else. I am right only if you are wrong. Attacking someone else only perpetuates hostility and anger (and rarely results in a change of beliefs). This aspect of atheism may appeal to certain personalities, but I would like to think (perhaps naively) that most people would prefer to define themselves positively, that is, not simply in terms of what they don't believe, but in terms of what they do believe.

So why isn't 'humanist' a title that people claim for themselves instead of 'atheist'? The two belief systems seem to be compatible in regard to belief in deities...

Hmmm. Perhaps this question will resolve itself I spend the summer brushing up on my humanist philosophy.