Arius
"Arius (born c. 250, Libya—died 336, Constantinople [now Istanbul, Turkey]) was a Christian priest whose teachings gave rise to a theological doctrine known as Arianism. Arianism affirmed a created, finite nature of Christ rather than equal divinity with God the Father and was denounced by the early church as a major heresy."
"Arianism, in Christianity, the Christological (concerning the doctrine of Christ) position that Jesus, as the Son of God, was created by God. It was proposed early in the 4th century by the Alexandrian presbyter Arius and was popular throughout much of the Eastern and Western Roman empires, even after it was denounced as a heresy by the First Council of Nicaea in 325."
- Excerpts taken from the Britannica:
The Editors of Encyclopaedia Britannica. "Arius." Encyclopedia Britannica, April 17, 2025. https://www.britannica.com/biography/Arius.
The Editors of Encyclopaedia Britannica. "Arianism." Encyclopedia Britannica, May 19, 2025. https://www.britannica.com/topic/Arianism.
The Controversy prior to the Council of Nicaea (325)
"Constantine's move to the East brought him to the centre of gravity of the empire. He also desired to visit the Holy Land and expressed a wish to be baptized in [the] Jordan. But his expectation of the Christian East was sadly disappointed. Just as the Donatist controversy in Africa had distressed him in the West, so now he found that the Greek churches had just become involved in sharp dissension, originating in an abstruse disagreement between bishop Alexander of Alexandria and his presbyter Arius. It had started as a local quarrel. But Arius had invoked weighty support outside Egypt, and now Alexander of Alexandria was being opposed by important bishops like the learned historian, Eusebius of Palestinian Caesarea, and his powerful namesake Eusebius bishop of Nicomedia...The Greek episcopate was split into two parties, with feeling running high. Constantine at once abandoned his proposed pilgrimage; he sent his ecclesiastical adviser, Hosius, bishop of Cordova, on a mission of reconciliation and inquiry, and decided to call a vast council of bishops at Ancyra (Ankara) after Easter 325." (Henry Chadwick, The Early Church, 129).
"On arrival at Alexandria Hosius sided with Alexander against Arius, and then went to Antioch in Syria to inquire into the support which Arius had been receiving form Eusebius of Caesarea and others. At a council of Antioch, where Hosius presided, Eusebius was excommunicated." (Henry Chadwick, The Early Church, 130).
"The Council of Nicaea, soon to be reckoned the first 'ecumenical' or world council because of the range of representation there, was attended by about 220 bishops, almost Greek...At the solemn opening on 20 May 325 Constantine urged the bishops to achieve unity and peace. He quickly made it clear that he deplored the censure of Eusebius of Caesarea and declared full support for his doctrines. But Eusebius' vindication did not mean that his friend Arius was to be upheld. The creed proposed for adoption by the council was sharply anti-Arian in its affirmation that the Son is 'of one substance with the Father.' Its concluding anathama condemned the propositions that the Son is metaphysically or morally inferior to the Father and belongs to the created order." (Henry Chadwick, The Early Church, 130).
~ Excerpts taken from Henry Chadwick's "The Early Church."