Ballentine's Law Dictionary p28

FIRST AMENDMENT

TRIPOLI TREATY 1796

​TREATY OF PEACE AND FRIENDSHIP.
Concluded November 4, 1796; Ratification advised by the Senate June 7,
1797; proclaimed June 10, 1797.

​ARTICLE XI.
As the Government of the United States of America is not in any sense founded on the Christian Religion; as it has in itself Religious freedom. no character of enmity against the laws, religion, or tranquility of Musselmen; and as the said States never have entered into any war or act of hostility against any Mehomitan nation, it is declared by the parties, that no pretext arising from religious opinions shall
ever produce an interruption of the harmony existing between the two countries.

1802 Jefferson's Letter to the Danbury Baptists

Supreme Court in 1878 and used to establish Separation of Church and State

Monte Made