No different than anyone else bro.
But it is different. It's practically impossible to become President as an atheist. You can have just about any belief you want, but if you claim to be an atheist, your chances of reaching higher office in this country are practically nil.
Why? Because religion is revered in this country and often goes unquestioned. "Because the Bible said so," is a legitimate justification for bigotry all around the world.
Religion matters. Quite a lot, actually.