Social Christianity is a heterogeneous tradition that has been cultivated by a diverse array of American Christians who shared in common an intuition that the source of social problems is more exterior than interior to the individual. Social gospelers have contended, in word and in deed, that sin infects not only individuals but also systems and structures; that salvation is not only personal but also societal; and that therefore participation in the struggle for a more just society is, for Christians, not so much optional as essential. This distinctly modern tradition first emerged in the antebellum period, but was overshadowed by older, benevolent, and bourgeois modes of reform until the early 20th century, when it gained a stronger foothold in both the institutional churches and the worlds beyond their walls. Social Christianity’s influence was never more formidable than during the New Deal era. It was during those pivotal decades, which saw the rise of a robust welfare state as well as of massive, faith-infused labor and civil rights movements, that social gospelers left their most lasting mark on American society. In the late 20th century and early 21st centuries, the tradition’s influence would decline precipitously, in no small part due to the success of a multifaceted backlash against social gospel ideas and movements. The rise of the modern right signaled, for social gospelers of all different kinds, a return to the wilderness.