The First Amendment in the Bill of Rights in the US Constitution asserts freedom of religious practice. Freedom from government interference in religious matters was therefore a founding US principle. Church and state are also kept separate.

There is no official religion, but more than half of the people are Protestant and about a quarter are Roman Catholic. Smaller percentages are Mormon, Jewish, and Muslim. More than one in 10 people claim no religion at all. Individuals—especially public figures—nevertheless often speak openly of their faith and religious beliefs.