by Giuseppe Monno
Arianism is one of the most significant Christological heresies in the history of the early Church. It takes its name from Arius, a presbyter of the Church of Alexandria in Egypt, active at the beginning of the fourth century. Arius was influenced by the teachings of Lucian of Antioch, founder of the exegetical school of Antioch and a proponent of subordinationism, the doctrine which affirms the superiority of the Father over the Son and the Holy Spirit, in contrast to the belief in the consubstantiality of the three Persons of the Trinity.
From around 315 onward, Arius began to preach that the Son of God is not eternal, but created: “there was a time when the Son was not” (Greek: ēn pote hote ouk ēn). According to Arius, Christ is the first and most exalted creature of the Father, created out of nothing (ex nihilo), though He was the instrument through whom all other things were made. In this view, the Son is subordinate to the Father both in nature and in dignity, and therefore cannot be considered fully God.
Arian teachings spread rapidly, aided by the support of numerous Eastern bishops and by the political backing of certain Roman emperors, particularly Constantius II and Valens. Arianism thus became a powerful force within Christianity, causing a profound theological and political division in the Roman Empire.
The principal opponent of Arianism was Athanasius of Alexandria (c. 295–373), first a deacon and later bishop of the same city. Athanasius vigorously defended the consubstantiality (homoousios) of the Son with the Father—that is, the teaching that the Son shares the same divine substance as the Father—rejecting every form of subordinationism. Because of his theological commitment, he was exiled multiple times and endured great hardship, yet his theology proved decisive for the establishment of Christian orthodoxy.
Arianism was first condemned at the Synod of Alexandria in 318 and then more authoritatively at the Council of Nicaea in 325, convened by Emperor Constantine. At this council, the Nicene Creed was formulated, affirming the full divinity of the Son and declaring Him to be “begotten, not made, consubstantial with the Father.”
Despite this condemnation, Arianism continued to survive in various forms. Some of these attempted to mediate between the Arian and Nicene positions (for example, Semi-Arianism). It was finally condemned definitively at the Council of Constantinople in 381, which reaffirmed and expanded the Nicene doctrine of the Trinity, including a full affirmation of the divinity of the Holy Spirit.
Nevertheless, Arianism did not disappear entirely. It was adopted by several Germanic peoples who converted to Christianity, such as the Visigoths, Ostrogoths, and Vandals, and persisted in certain regions of the West until the sixth century.