It is hard for us now to realize how continuous and almost universal had been the belief that the welfare of the state was bound up with religious uniformity. For more than a thousand years, and throughout Christendom, practically everybody except little bands of heretics and rebels believed that the institutional unity of the church was essential to the security of the state and the stability of the social order, and that it was the state’s duty to enforce this unity. That belief furnished the reason—and when not the reason, the excuse—for most of the persecutions that have occurred. Roman Catholics, of course, believed it, and it is still the official teaching of the Roman Catholic Church. But most Protestants also believed it. Only the Baptists and Quakers and some small separatist sects in Germany believed in religious liberty as a matter of principle. But the established and respectable bodies considered these as wild-eyed radicals. Episcopalians and Puritans who founded colonies in America brought with them this idea of a state church and a religious unity enforced by the police power, not because they were bigoted or cruel by preference but because they believed, as almost everybody had believed for centuries, that in no other way could a political society be strong enough to survive. Surprise is sometimes expressed at the “inconsistency” of the Puritans, who “came seeking religious liberty” and then persecuted the Quakers and Baptists. But there is no inconsistency, for they did not come seeking religious liberty. They came to establish a Puritan state. They had to learn religious liberty after they arrived, and they were rather slow in learning it. But even the vestiges of the colonial religious establishments withered away after the Revolution, and America became, in fact as well as in constitutional theory, a nation in which all churches, like all individuals, are free and equal before the law. A new epoch in the history of religion began when a nation was born which (_a_) disclaimed for its civil power the right and duty of giving special protection to a favored church, (_b_) declared implicitly, as the Virginia Bill of Rights in 1776 had done explicitly, that religion must be purely voluntary, and (_c_) abandoned the medieval political philosophy which justified intolerance on the theory that the state must enforce religious uniformity in the interest of its own stability and security. These new American conditions had, among others, three results that are of vital importance in connection with the present study: First, the removal of the repressive hand of government made it easier for new religious movements to spring up or for old ones to divide. Hence new divisions in the church arose in addition to those which had been imported from Europe. The divided state of the Christian forces became more acute and called more urgently for correction.