The Arian controversy was a series of Christian disputes about the nature of Christ that began with a dispute between Arius and Athanasius of Alexandria, two Christian theologians from Alexandria, Egypt. The most important of these controversies concerned the relationship between the substance of God the Father and the substance of His Son.
Emperor Constantine, through the Council of Nicaea in 325, attempted to unite Christianity and establish a single, imperially approved version of the faith. Ironically, his efforts were the cause of the deep divisions created by the disputes after Nicaea.
These disagreements divided the Church into various factions for over 55 years, from the time of the First Council of Nicaea in 325 until the First Council of Constantinople in 381. There was no formal schism.
Inside the Roman Empire, the Trinitarian faction ultimately gained the upper hand through the Edict of Thessalonica, issued on 27 February AD 380 by the then reigning three co-Emperors, which made Nicene Christology the state religion of the Roman Empire, and through strict enforcement of that edict. However, outside the Roman Empire, Arianism and other forms of Unitarianism continued to be preached for some time. The modern Roman Catholic Church and the Eastern Orthodox Church, as well as most other modern Christian sects, have generally followed the Trinitarian formulation, though each has its own specific theology on the matter.
History
Cause of the controversy
The "traditional account," presents the Arian controversy as "initially provoked by a priest called Arius." However, "the controversy surrounding Arius was an epiphenomenon of widespread existing tensions.” "Many of the issues raised by the controversy were under lively discussion before Arius and Alexander publicly clashed." "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." "In the fourth century there came to a head a crisis … which was not created by … Arius."
Revisionist accounts
"A vast amount of scholarship over the past thirty years has offered revisionist accounts of themes and figures from the fourth century." “The four decades since 1960 have produced much revisionary scholarship on the Trinitarian and Christological disputes of the fourth century. It is now commonplace that these disputes cannot simply be understood as … the Church's struggle against a heretic and his followers grounded in a clear Nicene doctrine established in the controversy's earliest stages. Rather, this controversy is a complex affair in which tensions between pre-existing theological traditions intensified as a result of dispute over Arius, and over events following the Council of Nicaea.”
"The diatribes of Gwatkin and of Harnack (published around the beginning of the 20th century), can today be completely ignored” (RH, 95). “More recent and more thorough examination of Arianism has brought a more realistic estimate of it."
Beginning of the controversy
"The fundamental problem in understanding … these controversies … (is that) the documentary evidence from this period is … fragmentary.:
R.P.C. Hanson quotes with approval "a paper by R. D. Williams." “Alexander of Alexandria, Williams thinks, had maintained that the Son … is a property or quality of the Father, impersonal and belonging to his substance. Properties or qualities cannot be substances …; they are not quantities. The statement then that the Son is idios to (a property or quality of) the Father is a Sabellian statement.”