Separation of church and state in the United States

"Separation of church and state" is a phrase used by Thomas Jefferson and others expressing an understanding of the intent and function of the Establishment Clause and Free Exercise Clause of the First Amendment to the Constitution of the United States which reads: "Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof..."

The phrase "separation of church and state" is generally traced to a by Thomas Jefferson, addressed to the Danbury Baptist Association in Connecticut, and published in a Massachusetts newspaper. Jefferson wrote,

Jefferson was echoing the language of the founder of the first Baptist church in America, Roger Williams who had written in 1644 of "[A] hedge or wall of separation between the garden of the church and the wilderness of the world." Article Six of the United States Constitution also specifies that "no religious Test shall ever be required as a Qualification to any Office or public Trust under the United States."

Jefferson's metaphor of a wall of separation has been cited repeatedly by the U.S. Supreme Court. In Reynolds v. United States (1879) the Court wrote that Jefferson's comments "may be accepted almost as an authoritative declaration of the scope and effect of the [First] Amendment." In Everson v. Board of Education (1947), Justice Hugo Black wrote: "In the words of Thomas Jefferson, the clause against establishment of religion by law was intended to erect a wall of separation between church and state."

...
Wikipedia