HOMOOUSIAN

in Christianity, an adherent of the doctrine formulated at the Council of Nicaea (325) to affirm that God the Son and God the Father are of the same substance. The council, presided over by the Roman emperor Constantine, intended the condemnation of Arianism, which taught that Christ was more than human but not truly divine. The use of homoousios (Greek: of one substance, or of one essence) in the Nicene Creed was meant to put an end to the controversy, but Arianism revived within the church, and it was not until 381 at the second ecumenical council (first Council of Constantinople) that a creed (also containing the word homoousios) was accepted as a definitive statement of orthodox belief.