A history of how the freethought movement fought to maintain a secular United States.

Although today it has largely faded from public memory, the American freethought movement played an important role in shaping the religious landscape of the United States. Without its influence, state and local governments might still demand that public officeholders subscribe to specific religious doctrines and prosecute those who question the existence of God or the authority of the Bible for blasphemy.

In American Freethought, David C. Hoffman traces the history of the freethought movement to discover the strategies that allowed it to endure and succeed in a fervently religious nation. Hoffman argues that American freethought has proceeded through four waves: a period of deism inspired by Thomas Paine's The Age of Reason and allied with Jeffersonian republicanism in the 1790s; a revival in 1825 that centered on the celebration of Paine's birthday and drew in the followers of utopian socialist Robert Owen; a "golden age of freethought" in the late 1870s that saw an unprecedented explosion of freethought publications and organizations together with a demand for the separation of church and state; and a final resurgence in the 1920s that helped realize the remarkable series of twentieth-century Supreme Court decisions that created America's present conditions of secularism.

Hoffman argues that the freethought movement was successful because it united people with a wide variety of religious outlooks—including deists, pantheists, Unitarians, Universalists, spiritualists, transcendentalists, Humanists, agnostics, and atheists—behind the idea that religion is freer and the state is more just when the government refrains from religious involvement.