Bogomils (bōˈgōmĭlz) [key], members of Europe's first great dualist church, which flourished in Bulgaria and the Balkans from the 10th to the 15th cent. Their creed, adapted from the Paulicians and modified by other Gnostic and Manichaean sources, is attributed to Theophilus or Bogomil, a Bulgarian priest of the 10th cent. The movement was intensely nationalistic and political, as well as religious, and reflected resentment of Byzantine culture, Slavic serfdom, and imperial authority. They vanished due to persecution and the expansion of Islam, but bits of their ideas and folklore persisted for centuries in Slavic lands.
See M. Loos, Dualist Heresy in the Middle Ages (1974).