Athanasius
Bishop of Alexandria, theologian and Father of the Greek Church (c. 296/298–373), a central and tenacious figure in the fourth-century Trinitarian controversies, best known for his relentless defence of the doctrine of the Son's consubstantiality with the Father (homoousios) against Arianism — the doctrine, prevailing across large sectors of the empire and often backed by successive Roman emperors, that Christ was a creature created by God and therefore neither coeternal with nor of the same divine substance as the Father. Present as a young deacon at the First Council of Nicaea (325), where the Nicene Creed condemning Arianism was formulated, Athanasius succeeded to the see of Alexandria in 328 and devoted the rest of his life — marked by five successive exiles imposed by pro-Arian emperors or ecclesiastical intrigue, amounting to more than seventeen years away from his see — to tirelessly defending Nicene orthodoxy in an extremely hostile political and ecclesiastical climate, giving rise to the Latin expression 'Athanasius contra mundum' ('Athanasius against the world') to describe his doctrinal isolation. His most influential theological work, On the Incarnation of the Word (De Incarnatione), articulates with remarkable clarity the central soteriological logic of orthodox Christianity: only if the incarnate Word is fully divine can his death and resurrection truly redeem humanity from corruption and death, an argument he made famous with the formula 'God became man so that man might become god' (by grace, not by nature). Also the author of an extraordinarily influential Life of Antony that popularised the ideal of Egyptian eremitic monasticism throughout the Christian world, and responsible for the earliest known list enumerating exactly the twenty-seven books that would constitute the New Testament canon (Festal Letter 39, 367 AD), Athanasius is regarded as one of the decisive architects of Christian Trinitarian orthodoxy and venerated as Father and Doctor of the Church in both East and West.