“Believing with you, that religion is a matter which lies solely between man and his God, that he owes account to none other for his faith or his worship, that the legitimate powers of government reach actions only, and not opinions, I contemplate with sovereign reverence that act of the whole American people which declared that their legislature should ‘make no law respecting an establishment of religion, or prohibiting the free exercise thereof;’ thus building a wall of separation between church and state … Adhering to this expression of the supreme will of the nation, in behalf of the rights of conscience, I shall see with sincere satisfaction the progress of those sentiments which tend to restore to man all his natural rights, convinced he has no natural rights in opposition to his social duties.”
Jefferson’s use of the phrase "wall of separation between church & state" gave us the language most frequently used in interpreting the Constitution’s Establishment clause.
★ THOMAS JEFFERSON. Letter to Danbury Baptist Church, printed in Aurora General Advertiser. [Philadelphia]: Published (Daily) at William Duane, Successor to Benjamin Franklin Bache, in Franklin-Court, Market-Street, February 1, 1802. #25964.99