This dissertation examines the life of Gerrit Smith, a wealthy land speculator who became well known in the nineteenth century for his philanthropy, his moral reform activity, and his political abolitionism. His speeches, pamphlets, broadsides, and correspondence reveal a complex and conflicted man who sought to live a Christian life in a sinful world. By tracing his religious evolution from orthodox Calvinism to the religion of reason, this study reveals how Smith evolved from a moderate moral reformer who supported benevolent associations and stressed voluntarism to a radical who argued that civil government had the duty to shield the exploited from their oppressors. His political abolitionism confronted the Democratic and Whig Parties by insisting that the original intent of the U.S. Constitution was anti-slavery, challenged William Lloyd Garrison's contention that moral suasion was the only just means to end slavery, and allowed him to argue that the federal government had to abolish slavery before slaves violently revolted against their oppressors.