I don't see how dividing people into those who believe in the supernatural versus those who do not has any political relevance. It seems like we would just be creating animosity for no good reason.
The characteristics of atheists that are relevant are the adherence to reason and a belief that religion should not enter into public policy. And many believers share those characteristics most of the time. I would turn the question around to be:
How can we reach out to the religious who have a sense that the fundamentalists are creating a real mess of our society?