The Radical Reformation was the response to what was believed to be the corruption in both the Roman Catholic Church and the expanding Magisterial Protestant movement led by Martin Luther and many others. Beginning in Germany and Switzerland in the 16th century, the Radical Reformation gave birth to many radical Protestant groups throughout Europe. The term covers both radical reformers like Thomas Müntzer, Andreas Karlstadt, groups like the Zwickau prophets and Anabaptist groups like the Hutterites and Mennonites.
In parts of Germany, Switzerland and Austria, a majority sympathized with the Radical Reformation despite intense persecution. Although the surviving proportion of the European population that rebelled against Catholic, Lutheran and Zwinglian churches was small, Radical Reformers wrote profusely and the literature on the Radical Reformation is disproportionately large, partly as a result of the proliferation of the Radical Reformation teachings in the United States.
Unlike the Catholics and the more Magisterial Lutheran and Reformed (Zwinglian and Calvinist) Protestant movements, some of the Radical Reformation abandoned the idea that the "Church visible" was distinct from the "Church invisible." Thus, the Church only consisted of the tiny community of believers, who accepted Jesus Christ and demonstrated this by adult baptism, called "believer's baptism".