We have solved by fair experiment, the great and interesting
question whether freedom of religion is compatible with order in
government, and obedience to the laws. And we have experienced
the quiet as well as the comfort which results from leaving
everyone to profess freely and openly those principles of
religion which are the inductions of his own reason, and the
serious convictions of his own inquiries.
Letter to the Baptist Association at Chesterfield Virginia, November 21, 1808, Andrew Lipscomb and Albert Bergh, The Writings of Thomas Jefferson, Vol. 16, p. 320.
I do not believe it is for the interest of religion to invite the civil magistrate to direct its exercises, its discipline, or its doctrines; nor of the religious societies that the general government should be invested with the power of effecting any uniformity of time or matter among them....Every religious society has a right to determine for itself the times for the exercises and the objects proper for them, according to their own particular tenets; and this right can never be safer than in their own hands, where the Constitution has deposited it.
Letter to Samuel Miller, January 23, 1808, Andrew Lipscomb and Albert Bergh, The Writings of Thomas Jefferson, Vol. 6, p. 428.