Doctrine rejected as false by religious authorities. In Christianity, the orthodox theology of the church is thought to be based on divine revelation, and heretics are viewed as perversely rejecting the guidance of the church. Numerous Christian heresies appeared from the 2nd century onwards. Early heresies included Arianism, the Monophysite heresy, Pelagianism, and Donatism. Some heresies, such as Montanism, expressed faith in a new prophet who added to the body of Christian revelation. Some types of Gnosticism were heretical branches of Christianity. The major means of combating heretics in the early church was excommunication. In the 12th–13th century, the Inquisition was established to combat heresy, and heretics who refused to recant were often executed. In the 16th century the Protestant Reformation brought an end to the doctrinal unity of Western Christendom, and the concept of heresy became less important in the various Christian churches, though it continues to exist. The concept of heresy also exists in Judaism, Buddhism, Hinduism, and Islam.