The fundamentalist–modernist controversy is a major schism that originated in the 1920s and 1930s within the Presbyterian Church in the United States of America. At issue were foundational disputes about the role of Christianity; the authority of the Bible; and the death, resurrection, and atoning sacrifice of Jesus Christ. Two broad factions within Protestantism emerged: fundamentalists, who insisted upon the timeless validity of each doctrine of Christian orthodoxy; and modernists, who advocated a conscious adaptation of the Christian faith in response to the new scientific discoveries and moral pressures of the age. At first, the schism was limited to Reformed churches and centered around the Princeton Theological Seminary which had fundamentalist faculty members found Westminster Theological Seminary when Princeton went in a liberal direction. However, it soon spread, affecting nearly every Protestant denomination in the United States. Denominations that were not initially affected, such as the Lutheran churches, eventually were embroiled in the controversy, leading to a schism in the United States.

By the end of the 1930s, proponents of theological liberalism had, at the time, effectively won the debate, with the modernists in control of all mainline Protestant seminaries, publishing houses, and denominational hierarchies in the United States. More conservative Christians withdrew from the mainstream, founding their own publishing houses (such as Zondervan), universities (such as Biola University), and seminaries (such as Dallas Theological Seminary and Fuller Theological Seminary). This would remain the state of affairs until the 1970s, when conservative Protestantism emerged on a larger scale in the United States, resulting in the rise of conservatism among the Southern Baptists, Presbyterians, and others.