The separation of church and state is widely considered to be a building block of American democracy,  but what did the founders really have in mind when they wrote "Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof” into the first amendment? And what's the deal with "one nation under God," and the whole swearing on the bible thing? Backstory's Ed Ayers and Brian Balogh lead today's civics lesson.