Arianism (âr´ēənĬz´əm), Christian heresy founded by Arius in the 4th cent. It was one of the most widespread and divisive heresies in the history of Christianity. As a priest in Alexandria, Arius taught (c.318) that God created, before all things, a Son who was the first creature, but who was neither equal to nor coeternal with the Father. According to Arius, Jesus was a supernatural creature not quite human and not quite divine. In these ideas Arius followed the school of Lucian of Antioch.
Rise of Arianism
Because of his heretical teachings, Arius was condemned and deprived of his office. He fled to Palestine and spread his doctrine among the masses through popular sermons and songs, and among the powerful through the efforts of influential leaders, such as Eusebius of Nicomedia and, to a lesser extent, Eusebius of Caesarea. The civil as well as the religious peace of the East was threatened, and Roman Emperor Constantine I convoked (325) the first ecumenical council (see Nicaea, First Council of). The council condemned Arianism, but the Greek term homoousios [consubstantial, of the same substance] used by the council to define the Son's relationship to the Father was not universally popular: it had been used before by the heretic Sabellius. Some, like Marcellus of Ancyra, in attacking Arianism, lapsed into Sabellianism (see under Sabellius).
Eusebius of Nicomedia used this fear of Sabellianism to persuade Constantine to return Arius to his duties in Alexandria. Athanasius, chief defender of the Nicene formula, was bishop in Alexandria, and conflict was inevitable. The Eusebians managed to secure Athanasius' exile, and when the Arian Constantius II became emperor, Catholic bishops in the East, e.g., Eustathius, were banished wholesale.
Athanasius' exile in Rome brought Pope Julius I into the struggle. A council wholly favorable to Athanasius, convened at Sardica (c.343), was avoided by the Eastern bishops and ignored by Constantius. The Catholics were left dependent on Rome for support. After the West fell to Constantius, the Eusebians reversed the decisions of Sardica in several councils (Arles, 353; Milan, 355; Boziers, 356), and Pope Liberius, St. Hilary of Poitiers, and Hosius of Cordoba were exiled. The victorious Arians, however, had now begun to quarrel among themselves.
Divisions within Arianism
The Anomoeans [Gr.,=unlike], followers of Eunomius and Aetius, were pure Arians and held that the Son bore no resemblance to the Father. The semi-Arian court party were called Homoeans [Gr.,=similar], from their teaching that the Son was simply like the Father as defined by Scripture. A third party called Homoiousians [Gr.,=like in substance] were largely prevented from joining the orthodox (Homoousian) party through a misunderstanding of terms. The Arians debated their differences at Sirmium (351–59). The final formula was an ambiguous Homoean declaration that Constantius imposed (359) on the church in two councils, Rimini (for the West) and Seleucia (for the East).
The voices of orthodoxy, however, were not silent. In the West St. Hilary of Poitiers and in the East St. Basil the Great, St. Gregory Nazianzen, and St. Gregory of Nyssa continued to defend and interpret the Nicene formula. By 364 the West had a Catholic emperor in Valentinian I, and when the Catholic Theodosius I became emperor of the East (379), Arianism was outlawed. The second ecumenical council was convoked to reaffirm the Nicene formula (see Constantinople, First Council of), and Arianism within the empire seems to have expired at once.
However, Ulfilas had carried (c.340) Homoean Arianism to the Goths living in what is now Hungary and the NW Balkan Peninsula with such success that the Visigoths and other Germanic tribes became staunch Arians. Arianism was thus carried over Western Europe and into Africa. The Vandals remained Arians until their defeat by Belisarius (c.534). Among the Lombards the efforts of Pope St. Gregory I and the Lombard queen were successful, and Arianism finally disappeared (c.650) there. In Burgundy the Catholic Franks broke up Arianism by conquest in the 6th cent. In Spain, where the conquering Visigoths were Arians, Catholicism was not established until the mid-6th cent. (by Recared), and Arian ideas survived for at least another century. Arianism brought many results—the ecumenical council, the Catholic Christological system, and even Nestorianism and, by reaction, Monophysitism.
See H. M. Gwatkin, Studies of Arianism (2d ed. 1900); J. H. Newman, The Arians of the Fourth Century (1933, repr. 1968); J. Pelikan, The Emergence of the Catholic Tradition (1971).