The religious change unleashed considerable discussion and rethinking, spawning a variety of groups and theological ideas. One group of devout reformers in Zurich, Switzerland asked why the Reformation had not sufficiently changed churches and individuals. They concluded that the problem was infant baptism, which was practised by both Catholics and Protestants and which brought everyone in society, Christians and non-Christians alike, into the church and corrupted it. In 1525, these devout reformers baptized themselves as believing adults and established a new church composed only of deeply committed Christians. In doing so, they earned the name "Anabaptists", which means "rebaptizers". Despite severe persecution (or perhaps because of it), the Anabaptist believers went out in all directions, preaching the gospel and baptizing converts. In particular, they won considerable numbers of converts in Germany and the Netherlands.
A more serious problem than persecution was doctrinal error (particularly strong expectations of the end times) which grew out of the religious confusion of the time and infiltrated the Anabaptist movement. Some Anabaptists began gathering in the city of Muenster in northwest Germany, near the border with the Netherlands, becoming a majority of the population. Jan of Leiden declared himself an endtimes prophet, seized the leadership of the Anabaptists in Muenster and attempted to set up the Kingdom of God by force. Muenster was overrun in 1535 by a Catholic/Protestant army and the Anabaptists there were executed.
In the Netherlands about the same time, the Anabaptists were joined by a former Roman Catholic priest named Menno Simons. He became such an influential leader that the Anabaptists were eventually renamed "Mennonites".