Athanasius was a deacon and secretary to the bishop of Alexandria at the time of the First Council of Nicaea (325), where the great question of the divinity of Christ was decisively settled against the Arians. At twenty-eight he was elected Patriarch of Alexandria, an office he held for forty-five years — though he spent seventeen of them in five separate exiles imposed by Arian emperors and bishops.
His most enduring work is the brief, luminous On the Incarnation, written in his youth: 'The Son of God became man so that we might become God.' He also wrote the foundational Life of Antony — the great desert father who had been his friend — which spread Christian monasticism across the empire and helped convert Augustine.
His Easter Letter of 367 is the first surviving document to list exactly the twenty-seven books of the New Testament as Sacred Scripture — defining the canon that the universal Church would accept. He died at Alexandria in 373; the post-Nicene Church called him 'the great Athanasius.' Cardinal Newman would write: 'His name will ever be remembered as the chief defender of our Lord's divinity in the early Church.'