The separation between the different forms of Protestantism began as early as the Reformation movements in Wittenberg and Zurich. Dissenters emerged who challenged the teachings of Luther and Zwingli and used the same theological principles to develop alternative strains of evangelical Christianity. Marked out by the unique features of their faith, including the practice of adult baptism and deep veins of spiritualism, and persecuted by both church and state, these so-called radical Protestants were forced underground and were unable to develop public churches. Despite ongoing persecution, however, the radicals continued to develop their own faith-based communities and cultivate supraregional associations based on similarities of belief and practice. Although these communities remained on the margins of mainstream Protestant history, they exercised a powerful influence on the development of the Lutheran and Reformed traditions, and indeed over time many aspects of radical religiosity became defining features of Protestantism tout court.
One Nation under God: The Religious Right and the Separation of Church and State in the United States