[Pt.] I. Late eighteenth-century religious liberty. Separation, purity, and anticlericalism -- Accusations of separation -- The exclusion of the clergy -- Freedom from religious establishments. [Pt.] II. Early ninteenth-century republicanism. Demands for separation: separating Federalist clergy from Republican politics -- Keeping religion out of politics and making politics religious -- Jefferson and the Baptists: separation proposed and ignored as a constitutional principle. [Pt.] III. Mid-ninteenth-century Americanism. A theologically liberal, anti-Catholic, and American principle -- Separations in society -- Clerical doubts and popular Protestant support -- [Pt.] IV. Late ninteenth- and twentieth-century constitutional law. Amendment -- Interpretation -- Differences -- An American constitutional right.