Indeed. Let us consult Madison again upon the subject.
the industry, and the morality of the priesthood, and the devotion of the people, have been manifestly increased by the total separation of the church from the State (Letter to Robert Walsh, Mar. 2, 1819).
Strongly guarded as is the separation between religion and & Gov’t in the Constitution of the United States the danger of encroachment by Ecclesiastical Bodies, may be illustrated by precedents already furnished in their short history (Detached Memoranda, circa 1820).
Every new and successful example, therefore, of a perfect separation between the ecclesiastical and civil matters, is of importance; and I have no doubt that every new example will succeed, as every past one has done, in showing that religion and Government will both exist in greater purity the less they are mixed together (Letter to Edward Livingston, July 10, 1822).
That is what he said. What he meant by it is how he wrote the Northwest Ordinance.