The Protestant Reformation was hardly a unified protest against the doctrines and practices of the Medieval church. Aside from the mainstream Lutheran, Anglican, and Reformed divisions, a variety of eddies and side currents also flowed through reform in the sixteenth century. There were Anabaptists, of course, as well as Spiritualists, Mystics, Pantheists, Anti-Trinitarians, and others in the so-called Radical Reformation. One of the most intriguing...