The Radical Reformation was a 16th-century response to both the perceived corruption in the Roman Catholic Church and the expanding Protestant movement led by Martin Luther. Focused primarily on the peasant class of Germany and the Low Countries, the Radical Reformation birthed many Anabaptist groups throughout Christendom.

Unlike not only the Catholics, but also the more mainstream Evangelical (Lutheran) and Reformed (Zwinglian and 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".

Early forms of the Radical Reformation were often millenarian, focusing on the imminent end of the world. This was particularly notable in the rule of John of Leiden over the city of Münster in 1535, which was ultimately crushed

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.

In addition to the Anabaptists, other strains of the Radical Reformation have been identified. Notably, George Hunston Williams, the great categorizer of the Radical Reformation, considered early forms of Unitarianism (such as that of the Socinians, and exemplified by Michael Servetus), and other trends that disregarded the Nicene christology still accepted by both Catholics, Orthodox, and the two larger protestant groups, as part of the Radical Reformation.

See also

• Protestant Reformation
• Anabaptist
  • Anabaptist persecution
• Martyrs Mirror