The endorsement of religious freedom in the first amendment to the Constitution of the United States represents a modern revolution in the relation between politics and religion. In American politics there has been continual disagreement about the meaning of this constitutional principle, and widely-held views of religious freedom include much philosophical confusion. This book shows how a plurality of religious convictions can be politically united only by a free debate among different religious convictions. The author demonstrates that religious freedom is a coherent political principle, and that this principle is the defining democratic commitment because all other political principles should be subject to assessment by the same free debate characterizing religious freedom. This book identifies the meaning of an authentically democratic constitution and the civility required of democratic citizens.