Arius

Arius served as a presbyter at Baucalis, one of the parish churches of Alexandria, under Bishop Alexander, and taught that only God the Father is unbegotten, without beginning and without source. The Son, in Arius's account, is the Father's first and greatest creation, brought into being before all ages to serve as the agent of the rest of creation, but not co-eternal with the Father and not of the same substance. His own summary line, preserved only because opponents quoted it to condemn it, was blunt: there was when the Son was not.

The stakes were not abstract. If the Son is a creature, however exalted, then what unites humanity to God in Christ is itself something less than full divinity, and salvation rests on shakier ground than the church at large was prepared to accept. Bishop Alexander deposed Arius locally around 321, but Arius had allies among influential bishops in the East, chiefly Eusebius of Nicomedia, and the dispute spread through the empire's Christian communities quickly enough that the emperor Constantine, only recently converted and eager for a unified church, called a general council to settle it.

Almost nothing survives in Arius's own voice. His letter to Eusebius of Nicomedia and fragments of a verse work called the Thalia, meant to popularize his teaching in a form ordinary people could sing, are preserved only inside the writings of the opponents who quoted them to refute them, chiefly Athanasius, who spent much of his career as Alexander's successor prosecuting the case against him.

Constantine convened bishops from across the empire at Nicaea in 325. The council produced a creed declaring the Son homoousios with the Father, of one substance, co-eternal and uncreated, directly rejecting Arius's teaching, and Arius himself was exiled. The condemnation did not end the argument. Constantine later readmitted Arius to communion under pressure from his Eastern allies, and for the better part of the fourth century the empire's bishops split repeatedly over rival creeds, exiles and reinstatements that tracked the shifting sympathies of successive emperors rather than a settled theological consensus. Arius died in Constantinople in 336, and the wider controversy that carried his name was not closed until the First Council of Constantinople in 381 reaffirmed and extended the Nicene formula.

Arian Christianity did not simply disappear with that ruling. Ulfilas, a fourth century Gothic bishop trained in the Eastern church during the years Arian theology held real influence there, translated scripture into Gothic and evangelized the Goths in a non-Nicene form of Christianity that spread with them into the Vandal, Lombard and Visigothic kingdoms, persisting in parts of Western Europe for two more centuries after Nicaea and Constantinople had settled the question for the imperial church.

Modern scholarship treats the label "Arianism" with some caution. Because Arius's own writings survive only as fragments embedded in hostile sources, and because later figures such as Eunomius pushed subordinationist Christology further than Arius himself is known to have gone, historians debate how far the developed "Arian" theology of the following decades should be read back onto Arius the man rather than onto a movement that grew past him.