Philip Schaff is considered the founder of the discipline of church history in America, and he was the foremost practitioner of that discipline in nineteenth-century America. In this book Stephen R. Graham provides the first in-depth treatment of Schaff's analysis of religion in American and, by means of that study, examines not only Schaff's thought but also the development of religion in the United States in the nineteenth century. Topics covered include the three "threats" to American Christianity as conceived by Schaff -- sectarianism, romanism, and rationalism; Schaff's understanding of the American experiment of separation of church and state; Schaff's conception of America as playing a unique role in world and Christian history; and Schaff's contributions to ecumenism.