First Council of Nicaea

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First Council of Nicaea Article

Did the Council of Nicaea settle the matter of Arianism?

Written and fact-checked by The Editors of Encyclopaedia Britannica

Not remotely. Arianism was actually the official orthodoxy of the Eastern Roman Empire until 381, when the Council of Constantinople declared the doctrine of the Trinity—that the Father, the Son, and the Holy Spirit are three equal parts of the single Godhead.