Although it is almost certain that various Presidents were non-practicing, deistic or even atheistic in private; all of them so far have come from Christian traditions. Even Obama's early Islamic influences stem from that Abrahamic tradition; as would a hypothetical Jewish president.
ive never really understood this assumption that Obama is an atheist. Maybe he is, maybe he isn't (it seems to stem from the slightly elitist assumption that smart people cannot be religious) but he carries himself in the Christian tradition. Even if he was an atheist, he wouldn't stop being a Christian somehow.
I don't think he's secretly an atheist either. Watch his Charleston funeral speech and spontaneous Amazing Grace. That didn't look at all contrived. But it's obvious he doesn't take very many things in the Bible literally.
