BOGOMILS (FRIENDS OF GOD). - A Christian heretical sect that appeared in Bulgaria between the first and second halves of the 10th century. The Bogomils derive their name from their leader, the priest Bogomil (in Bulgarian *bogumil*, "dear to God"). Although the origins of Bogomilism are still obscure, it is certain that this "haeresis Bulgarorum" arose from various preceding heresies, particularly the Manichaeans, Paulicians (in Thrace and Macedonia, 8th century), Byzantine iconoclasts, and more immediately from the Messalians, according to the testimony of Euthymius (PG 132, 1290). The sect soon spread throughout Bulgaria and under various other names (Cathars, Bulgarians, Albigensians) in the Balkans and other European regions, even reaching Russia.
At the foundation of their doctrinal system lies a dualistic-Gnostic principle of distinctly Manichaean character, which admits God as the creator of all that is spiritually good and eternal, both in man and in the world, and the Devil as the author of evil, of the contingent, of the material and corporeal. Rejecting the Old Testament, most of the Sacraments—especially Marriage—the sacred images, and denying Purgatory, the Bogomils regarded worship as consisting in the adoration of God "in spirit and truth," and in an austere ascetic life.
The movement, not immediately repressed, experienced periods of great development and of pause: development under Peter (927-69) in Bulgaria and later in Bosnia and throughout the Balkans; pause, already in 1019 with Byzantine rule and subsequently with the fierce persecutions mounted against them by bishops and councils (1211, 1325, 1360, etc.), emperors, and Bulgarian kings in the 12th-14th centuries. Preachers and missionaries, Dominicans and Franciscans, were sent by the Popes in the 13th and 14th centuries, especially to Bosnia where they also achieved important successes, such as the conversion in 1402 of 50,000 dissenters by the Conventual Franciscans (L. Wadding, *Annales Ord. Min.*, an. 1402, Quaracchi 1931, n. 11). But the Bogomils' strongest doctrinal opponent was the great theologian Cosmas, a Bulgarian priest (and bishop) of the 10th century, who exposed the founder and refuted his doctrines one by one, calling the people back to the true faith. Fierce opposition to the Bogomils was also mounted by Patriarch Theophilus and the monk Theodore in the 14th century. Yet the heresy, given the fanaticism of its adherents, spread to other parts of Europe and Bogomils appeared, especially mingling with the Cathars or Albigensians, with whom they ultimately identified, in Dalmatia, Italy, France, Spain, Germany, England, and elsewhere. The Slavic Bogomil heresy, with its connections, influenced all the heretical movements of the West before the advent of Luther.