Separation of church and state" is paraphrased from Thomas Jefferson and used by others in expressing an understanding of the intent and function of the Establishment Clause and Free Exercise Clause of the First Amendment to the United States Constitution which reads: "Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof..."
The principle is paraphrased from Thomas Jefferson's "separation between Church & State." It has been used to express the understandings of the intent and function of this amendment, which allows freedom of religion.