How can athiesm be an intellectual choice, when the most powerful man in the world is a christan?

The current president of the U.S is a professed christian. If anybody knows anything about the facts wouldn't you think this very important individual would know first? Why would the leading figure of the most powerful nation on earth consider himself a part of a so-called cave-man ideology such as christianity. Apparently our president is not convinced by modern evolution theory. Makes you wonder how strong the theory of evolution really is?