In the second of this three-volume history Gary Dorrien tells the story of American theological liberalism in its heyday, exploring the diversity of liberal theologians and schools of thought, as well as the central importance of liberal debates over idealism, realism, naturalistic empiricism, and "making Christianity modern". Breaking with previous interpretations, he treats Reinhold Niebuhr and Paul Tillich as theorists of a "neoliberal" position within the liberal tradition.