Arius

Arius (/əˈraɪəs, ˈɛəri-/; Koinē Greek: Ἄρειος, Áreios; 250 or 256 – 336) was a Cyrenaic presbyter, ascetic, and priest. Traditionally, it was claimed that Arius was the founder of the doctrine of Arianism but, more recently, Rowan Williams stated that "Arius' role in 'Arianism' was not that of the founder of a sect. It was not his individual teaching that dominated the mid-century eastern Church."

It is traditionally claimed that his teachings about the nature of the Godhead in Christianity, which emphasized God the Father's uniqueness and Christ's subordination under the Father, made him a primary topic of the First Council of Nicaea convened by Emperor Constantine the Great in 325. However, subordinationism was almost universally accepted by Christian theologians of that era, with the notable exception of Athanasius of Alexandria.

After the Roman Emperors Licinius and Constantine legalized and formalized Christianity, Constantine sought to unify the newly recognized Church and remove theological divisions. The Christian Church has long been divided by disagreements on Christology – specifically about the nature of the relationship between the Father and the Son. "The views of Arius were such as … to bring into unavoidable prominence a doctrinal crisis which had gradually been gathering. … He was the spark that started the explosion. But in himself he was of no great significance."

Homoousian Christians, particularly Athanasius of Alexandria, used Arian and Arianism as epithets to describe those who disagreed with their doctrine. However, "'Arianism' as a coherent system, founded by a single great figure and sustained by his disciples, is a fantasy … based on the polemic of Nicene writers, above all Athanasius."

The Nicene Creed "was constructed as a deliberately anti-Arian document." "All the more obnoxious doctrines of Arius and his followers are struck at in the most impressive way." Arius's theology is described as imputing there was a time before the Son of God existed—that is, when only God the Father existed.

Despite concerted opposition, Arian Christian churches persisted for centuries throughout Europe (especially in various Germanic kingdoms), the Middle East, and North Africa. They were suppressed by military conquest or by voluntary royal conversion between the fifth and seventh centuries.