Writing in Religion and American Culture, Stephen J. Stein said the book is "not a story of religion in isolation from the rest of American life", but a work that has as a major emphasis the theme of Americanization, of the symbiotic relationship between religions and cultures.

Williams's book widely considered the best of its kind, is a comprehensive introduction to the religious history of the United States and the traditions out of which it arose, from colonial times through the late twentieth century. Now including an updated bibliography, it presents descriptions of major religious traditions and introduces distinctive American innovations. Included are not only Christianity, Judaism, and Islam, but African American, Native American, and Asian American traditions. The peace churches, "liberal" churches, and Mormonism also are discussed.