The Reformation Simplified SERIES: The "Radical" Reformation

The Radical Reformation is a term usually referring to those 16th century groups who rejected both the Roman Catholic tradition and the ongoing Protestant alternatives to it, in the name of what they considered truer forms of Christianity, most notably those who became known as Anabaptists. As a result, they were persecuted by Catholics and Protestants alike and their ideas and lives were bitterly attacked, often without a genuine knowledge of what they stood for.
Early forms of the Radical Reformation were often millenarian, focusing on the imminent end of the world.
In contrast to Roman Catholicism, mainstream Evangelical ( Lutheran) and Reformed ( Zwinglian, Calvinist) Protestant movements, the Radical Reformation generally abandoned the idea of the "Church Visible" as distinct from the "Church Invisible." Thus, the Church only consisted of the tiny community of believers, who accepted Jesus Christ by adult baptism, called "believer's baptism".
Later forms of Anabaptism were much smaller, and focused on the formation of small, separatist communities. Among the many varieties to develop were Mennonites, Amish, and Hutterites.
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And they that understand among the people shall instruct many:
                                  yet they shall fall by the sword, and by flame,
                                                    by captivity, and by spoil, many days.
                                                  Daniel 11:33