Many atheists don't make a big deal out of their atheism. It's not really a big part of our lives. I don't make a big deal out of the fact that I don't believe that aliens have probed me or that I don't believe in Santa Claus.
I am an atheist because I am a skeptic. I am a skeptic because I was taught to be eithical. I was taught that if you respect life, then you respect reality and you respect truth. Religion of course, is a lie.
Here is a list of atheists that we know to be atheists. You decide whether they've actually contributed anything.
http://www.celebatheists.com/
I would put any of them against people like Mother Teresa, Jerry Falwell Oral Roberts or George Bush.