This chapter investigates debates around the First Amendment in the nineteenth century. In 1801, President Thomas Jefferson wrote to the Danbury Baptists of Connecticut that the First Amendment built “a wall of separation between Church & State.” Although not central to interpreting the First Amendment in the nineteenth century, Jefferson’s metaphor became the dominant interpretation in twentieth-century jurisprudence. This chapter examines whether citizens, public figures, and the courts endorsed a theory similar to Jefferson’s, and it finds they did not. Instead, the national practice endorsed public Christianity, building upon that faith’s majority status. At the same time, three groups posed definite challenges to this consensus. Freethinkers raised doubts about both Christianity and its socially privileged status. Roman Catholics had to defend their rights to religious practice. Mormon practice of plural marriage, however, went beyond the population’s willingness to tolerate and so was opposed by the power of the federal government.

David J. Brewer is famous for announcing in 1892 “this is a Christian nation” from the bench of the United States Supreme Court. He believed that Christianity justified an official separation of church and state while remaining the foundation of all human law. A liberal Congregationalist who was comfortable straying from literal readings of the Bible, Brewer spoke often in public on Christianity although his religious faith rarely surfaced in his judicial decisions. His many public speeches allow us to see how religion underlay his opposition to economics regulations as part of an influential conservative voting bloc on the Fuller Court at the turn of the century. Brewer’s stance against appeals in criminal trials relied upon his belief that flawed human justice and perfect divine justice played different roles. Brewer’s work in the peace movement was supported by a hope that it helped to hasten the Second Coming of Christ.