Anabaptist

Anabaptists are Protestant Christians. The word anabaptism comes from the Greek language, meaning "to baptize again". The followers of these movements hold that people should be baptized after they are believers, denying infant baptism. This is called believer's baptism. Infants, by their doctrine, can not be validly baptized, as they cannot decide how they want to achieve salvation. 
They arose as part of the Radical wing of the Reformation of 16th century Europe. The best-known Anabaptists today are the Mennonites, the Amish, and the Hutterites.