How did the Christian Right come to predominate in the Republican Party? Why, on the other hand, do secular and religiously liberal beliefs largely prevail in the Democratic Party? Our understanding of the rift between the Democratic and Republican parties -- a rift in many ways fueled by religious beliefs -- requires an analysis of the entire spectrum of religious and nonreligious players in the American political process and how their influence has evolved over a long period of time. Employing a sizeable collection of data on party members, activists, and elites, Geoffrey Layman examines the role of religion in the Democratic and Republican parties, and the ways in which religion has influenced the political process from the early 1960s through the late 1990s. Using a wide variety of sources, including the American National Election Studies -- the major academic survey of the American electorate -- Layman reveals a vast and subtly differentiated landscape of political life and a more vivid basis upon which to analyze the ever-widening chasm between the parties. Layman investigates a broad spectrum of religious variety, citing differences between African American Protestants, white evangelical Protestants, Roman Catholics, Jews, nonreligious or seculars, and smaller religious groups, as well as political cleavages within these faith traditions. With his broad-based and thorough analysis, he counters the often narrow focus and incendiary rhetoric of many of the "culture war" debates.