Obama is the WASP Ticket

Obama was raised by his Agnostic White mother and his Protestant White Grand-Parents (When hid lived in Indonesia, he was also raised by his Asian (probably) Muslim step-father). Obama doesn't talk about religion in his autobiography Dreams of My Father (at least, not in the part I read; the book is quite boring).

Religion in the USA matters. In fact, Americans would prefer a homosexual to an atheist (or at least that is what they say when answering one of those rushed surveys). According to that same survey, 94% would vote for a Catholic.

Note that this does not mean that for 94%, a candidate's religion doesn't matter, just that they would consider voting for a candidate of said religion.

Oddly, the survey doesn't ask if Americans would be willing to vote for a Protestant. 

Anyway, Obama is Protestant, Biden is Catholic. Romney is Mormon, his running mate is Paul Ryan is Catholic.