Among the features peculiar to the political system of the United States is the perfect equality of rights which it secures to every religious sect. [...] Equal laws protecting equal rights, are found as they ought to be presumed, the best guarantee of loyalty, and love of country; as well as best calculated to cherish that mutual respect and good will among citizens of every religious denomination which are necessary to social harmony and most favorable to the advancement of truth.
Letter to Jacob De La Motta, printed in "Letters and Other Writings of James Madison, vol. 3" (1867), August 1820.