Is it unheard of to be an athiest and a Republican?

Here is my question. I am an athiest. I believe in nothing. I am also a Republican. I believe in lower taxes, smaller government, individual freedom, gun rights, law and order, and a strong national defense. I differ with most Republicans in that I am pro choice and pro gay rights. I consider myself a Barry Goldwater conservative. I don't like the influence Pat Robertson and those inbreeds in the Christian Right and the Moral Majority have on the party. The other day, my aunt, who is a devout Catholic, and a single issue voter (pro life) says, "How can you be an athiest and a Republican?" In reality, I am probably a LOT more conservative than she is on fiscal issues. My question is, is it that unheard of to be an athiest and a Republican? Dumb question. Just wondering.