The slavery debates in the antebellum United States sparked a turning point in American theology. They forced moderately antislavery Protestants, including William Ellery Channing, Francis Wayland, and Horace Bushnell, to reconcile their contradictory loyalties to the Bible and to antislavery reform. Unable to use the letter of the Bible to make a scriptural case against slavery in itself, the moderates argued that although slavery had been acceptable in biblical times, it had become a sin. Antislavery Protestantism required a theory of (...) moral progress, a deeply unorthodox idea that became fundamental to the development of late nineteenth-century liberal Protestantism. The antislavery argument from moral progress, along with the moral progress represented by abolition, established a progressive conception of revelation that would be further developed by late nineteenth-century liberal theologians, including Newman Smyth, Lyman Abbott, and Theodore Munger. (shrink)