In contrast to the late antiquity , the execution of heretics was much more easily approved in the late Middle Ages , after the Christianization of Europe was largely completed . The first known case is the burning of fourteen people at Orléans in 1022 . In the following centuries groups like the Bogomils , Waldensians , Cathars and Lollards were persecuted throughout Europe . The Fourth Council of the Lateran ( 1215 ) codified the theory and practise of persecution . In its third canon , the council declared : '' " Secular authorities , whatever office they may hold , shall be admonished and induced and if necessary compelled by ecclesiastical censure , . . to take an oath that they will strive . . to exterminate in the territories subject to their jurisdiction all heretics pointed out by the Church . " '' In the process of eliminating these heretical movements , Church officials , especially members of the Inquisition , made widespread use of torture to provoke confessions . Heretics who refused to recant their beliefs were hanged or burnt alive . At the Siege of Béziers during the Albigensian Crusade ( launched to eliminate the Cathars in Languedoc , crusaders under the direction of a papal legate , Arnaud Amalric killed an estimated 20,000 people , both Cathars and orthodox Catholics
Siege of Béziers
Massacre at Béziers
History of Christian thought on persecution and tolerance