The half century following the American Revolution witnessed the transformation of American Christianity. The passion for equality, says Hatch, brought about a crisis of religious authority in popular culture, introduced new and popular forms of theology, witnessed the rise of minority religious movements, reshaped preaching, singing, and publishing, and became a scriptural foundation for 19th-century American individualism.

Hatch examines five distinct traditions or mass movements that emerged early in the 19th century: the Christian movement, the Methodists, the Baptists, the black churches, and the Mormons. Each was led by young men of relentless energy who went about movement building as self-conscious outsiders, however diverse their theologies and church organizations. Hatch points out, they all offered the unschooled and unsophisticated compelling visions of individual potential and collective aspiration.

More effectively than religious movements in other modern industrial societies, these denominations embraced people without regard to social standing and challenged them to think, interpret Scripture, and organize the church for themselves. The religious populism that resulted remains among the oldest and deepest impulse in American life.