A major reevaluation of American religious history. Finke and Stark (both Sociology/Purdue) rewrite the script by considering churches as ``firms'' competing for members in free-market America, and by unearthing long-buried surveys that provide eye-opening information about why and how different denominations corner the market. The authors begin by puncturing the convention of colonial America as a hotbed of religiosity. In fact, only 18% of colonists were ``churched,'' while today 62% of Americans claim membership in a congregation (in other words, America is an ever-more bullish religious market). In 1776, Congregationalists held sway, but as ossification set in (through elite clergy, large congregations, and liberalization), they were surpassed by Methodists, who offered dynamic itinerant preachers and a down-home teaching that stressed personal conversion. Eventually, the traditionalist Baptists overtook the Methodists. Finke and Stark discern the same pattern throughout the centuries: As a church grows wealthier, larger, and more liberal, it loses its fervor and, in time, its adherents. Roman Catholicism, America's largest denomination, remains a special case because of its international base and hierarchical structure. But here, too, success comes from an ``intense faith with a vivid sense of otherworldliness,'' complemented by home-grown parishes and parochial school systems. The same reasoning leads to the authors' revolutionary conclusion that religious ecumenism is doomed. Growing, vibrant churches, they find, inevitably oppose ecumenism: Witness American Protestantism today, where the National Council of Churches steadily loses influence while the mainstream relocates itself in the fundamentalist Southern congregations. ``The primary feature of our religious history,'' Finke and Stark conclude, is that ``the mainline bodies are always headed for the sideline''--a knockout punch, backed by scholarly dispassion and reams of statistics, sure to raise howls of protest from religious liberals and smug smiles from traditionalists. For both species, essential reading.