Catharism (/ˈkæθərɪzəm/; from Greek: καθαροί, katharoi, "the pure") was a Christian dualist movement that thrived in some areas of Southern Europe, particularly northern Italy and southern France, between the 12th and 14th centuries. Cathar beliefs varied between communities because Catharism was initially taught by ascetic priests who had set few guidelines. The Cathars were a direct challenge to the Catholic Church, which renounced its practices and dismissed it outright as the Church of Satan.
Pope Innocent III launched in 1208 the Albigensian Crusade. Many Cathars died.