A medieval Christian gnostic heretical sect that flourished in southern France, especially in the Provençal region. One branch of the sect, originating in the region of Albi, gave rise to the name of followers as Albigenses.
As early as the 1100s, a form of dualism that held that Satan was, though a creature of God, an immensely powerful being, appeared in southern France and in the Rhine Valley. Its immediate source may have been beliefs brought back from the Holy Land by crusaders. Within a decade, a more extreme dualism that argued for the existence of Satan prior to the creation of the universe appeared. The dualists in France made common cause with the Bogomil dualists of the southern Balkans and by 1180 had become a significant force in southeastern France and northern Italy. Cathar belief was also strong in Lombardy and the Rhineland. The Roman Catholic Church started a crusade against the Cathars of southern France, centered upon the town of Languedoc. By 1230 the Albigensians were eradicated.
What little we know concerning the Cathar belief and practice derives largely from a Cathar ritual from Provence, recorded in a thirteenth-century manuscript, and from the proceedings of the Roman Catholic inquisitors who ruthlessly persecuted the sect. The group has roots that go back to Manicheanism and origins in the theological problem of the place of good and evil in Christian doctrine. The Cathars believed a dualist concept of two gods or principles. The evil god Satan or Lucifer ruled the material world, which was a purgatorial condition for angels or divine souls imprisoned in flesh after the primal war in heaven. Humans could only recover the divine kingdom through a spiritual rebirth, becoming a vehicle for the Holy Ghost, otherwise death would not bring release. A man who died without such a spiritual rebirth would face reincarnation again and again, in human or animal form.
An interesting modern echo of the Cathari and its doctrine of imprisonment in the flesh through various incarnations is found in the strange claim of a modern British physician Arthur Guirdham that he has verified information that he and a group of other individuals were reincarnations of Cathars who were brutally persecuted in Languedoc, France, during the twelfth century.
Sources:
Birks, Walter. The Treasure of Montsagur: A Study of the Cathar Heresy and the Nature of the Cathar Secret. U.K.: Crucible, 1987.
Guirdham, Arthur. The Cathars and Reincarnation. London: Neville Spearman, 1970.
Lea, H. C. History of the Inquisition in the Middle Ages. 3 vols. New York: Harper and Bros., 1888.
Russell, Jeffrey Burton. Witchcraft in the Middle Ages. Ithaca, N.Y.: Cornell University Press, 1972.
Wakefield, Walter, and Austin P. Evans. Heresies of the High Middle Ages. New York, 1969.