heresy

Denial of, or deviation from, orthodox religious belief. The concept exists in most organized religions with a rigid, dogmatic system. The early Christian Church fought against heresies such as Arianism and Nestorianism. In the Middle Ages, the Catholic Church set up the Inquisition to fight heresy. After the Reformation, the Catholic Church described Protestants as heretics because of their denial of many papally defined dogmas, while Protestants applied the term to those who denied their interpretation of the major scriptural doctrines. Persecutions for heresy were common in most parts of Christendom until relatively recently.

World Encyclopedia. Philip's, 2005.