The Bill of Rights decoupled religion from the state, in part because so many religions were steeped in an absolutist frame of mind—each convinced that it alone had a monopoly on the truth and therefore eager for the state to impose this truth on others. Often, the leaders and practitioners of absolutist religions were unable to perceive any middle ground or recognize that the truth might draw upon and embrace apparently contradictory doctrines.
The framers of the Bill of Rights had before them the example of England, where the ecclesiastical crime of heresy and the secular crime of treason had become nearly indistinguishable. Many of the early Colonists had come to America fleeing religious persecution, although some of them were perfectly happy to persecute other people for their beliefs. The Founders of our nation recognized that a close relation between the government and any of the quarrelsome religions would be fatal to freedom—and injurious to religion.