There are plenty of conservative atheists here.
Please this recent FR thread and my post on the subject: Reagan Was Right, ACU Wrong: Atheism Is Enemy of America. I also direct your attention to the comment by FReeper stalwart xzins:
Conservatism is incompatible with atheism. Atheism is amoral and directionless. Conservatism has morality, meaning, purpose, and direction....all from God.
There is but one King in America and that's Almighty God.