This tension reached a climax during the Reformation and post-Reformation era. Wilken includes chapters on Lutheran Germany, Calvinist and Zwinglian Switzerland, and on Catholic-Protestant battles in France, the Netherlands, and England. Readers may be surprised to learn how often it was not just Protestants but also Catholics who turned to liberty in defense of their religious beliefs. Nuns in Germany, clergyman in Switzerland, Benedictine abbots in France, and papist lawyers in England all appealed to their consciences in the face of Protestant persecution. Indeed, while Reformation history is full of Catholic oppression of Protestants, it is equally full of Protestants oppressing, persecuting, and even forbidding Catholic worship.
It is ultimately the Englishmen—Roger Williams, John Owen, William Penn, and John Locke—to whom America and the West are indebted for their conception of religious freedom. Williams argued that liberty of conscience applied to all men equally, including dissenting Christians, Jews, Muslims, and even the hated Catholics. He also “severed the link between the two tables of the law,” meaning that he rejected any role for the state in the affairs of the church and vice versa. Owen, in turn, interpreted Tertullian’s earlier cited argument to mean that “liberty of conscience is a natural right” rather than one created and protected by the state. Penn, meanwhile, argued that this liberty of conscience necessarily extended to public worship. Locke, finally, incorporated some of these elements, but went even further by arguing that religious communities are fundamentally voluntary societies composed of individuals possessing “free and spontaneous” rights.For instance the Calvinist covenanters like Samuel Rutherford and John Knox who were "good" on resistance to tyrants in the face of Romans 13 were still defending Calvin having Servetus put to death for denying the Trinity. By the time of the American Founding, John Witherspoon and his Presbyterians had accepted liberty of conscience as an unalienable right.