[BlueSkyJaunte]

The exact words "separation of Church and State" actually came from a letter written by T. Jefferson (yes, that one) in 1802. However the idea is found directly in the unamended constitution, Article VI, Section III

"but no religious test shall ever be required as a qualification to any office or public trust under the United States."

Joseph Story comments:

"The remaining part of the clause declares, that 'no religious test shall ever be required, as a qualification to any office or public trust, under the United States.' This clause is not introduced merely for the purpose of satisfying the scruples of many respectable persons, who feel an invincible repugnance to any test or affirmation. It had a higher object: to cut off forever every pretence of any alliance between church and state in the national government. The framers of the constitution were fully sensible of the dangers from this source, marked out in history of other ages and countries; and not wholly unknown to our own. They knew, that bigotry was unceasingly vigilant in its own stratagems, to secure to itself an exclusive ascendancy over the human mind; and that intolerance was ever ready to arm itself with all the terrors of civil power to exterminate those, who doubted its dogmas, or resisted its infallibility."

Source of Material:

Commentaries on The Constitution of The United States by Joseph Story Vol. III, Page 705-709. De Capo Press Reprints in American Constitutional And Legal History series, Da Capo Press NY 1970 (Joseph Story's Commentaries were originally published in 1833)