His tenure was marked by his conflict with the Meletian Church in Egypt, and with the pro-Arian bishops within and outside his jurisdiction. Alexander did not enforce the canons of Nicaea with respect to the Meletian bishops in Egypt, and Athanasius met with strong resistance upon his insistence on the Council of Nicaea’s decisions.
The Meletians made cause with Arianism, whose strength in the East was supported by the pro-Arian Constantine the Great. Athanasius was dismissed from his see by a synod of bishops in Tyre in 335, and Emperor Constantine exiled him to Trier. After Constantine’s death (July 22, 337) the pro-Orthodox emperor Constantine II reinstated Athanasius.
Athanasius’s main opponents were now the Arians, in part because of the support they enjoyed among the conservative anti-Nicaean bishops of the East as well as in the imperial court of some of the emperors. Indeed, Athanasius’s periods of exile correspond to pro-Arian emperors or caesars of the East exercising their religious policy.
Athanasius was exiled again in 339 because of resentment of bishops in the east, led by Eusebius of Nicomedia, to Constantine II’s rejection of the decision of the Synod of Tyre and because these bishops were supported by the emperor of the east, Constantius II. Following official recognition by Pope Julius I of Rome and the Council of Sardica (343), which had been convoked by Constans, the emperor of the West, Constans himself exerted pressure on Constantius II, and Athanasius was reinstated in 346.
Constantius II became sole emperor after the assassination of Constans in 350, and Constantius was free to enforce his pro-Arian policy. Synods and letters denouncing Nicaea and its strongest supporter led Athanasius to flee from arrest. From 356 to 361 he hid among the monks of Egypt, although he remained in control of the pro-Nicene clergy through an intelligence network.
Emperor Julian the Apostate recalled him in 361 and because of his popularity and success in unifying the pro-Nicene parties in Egypt he was forced to leave Alexandria in 363 until the death of Julian the same year permitted his return. The pro-Arian emperor Valens (364–378) exiled Athanasius in 365 but in 366 sought his support against the Goths who were sweeping across North Africa, and he was reinstated on February 1. He remained bishop until his death in 373.
Athanasius’s theology must be reconstructed from his works, which were composed for specific occasions such as sermons or specific problems such as commentaries, apologia, or polemical tracts particularly against the Arians. Athanasius described the qualities of God in apophatic terms (such as inconceivable and uncreated) and rejected anthropomorphism, which reflected the Alexandrine tradition and its debt to Platonist philosophy. God is the source of all creation by his will.
God created and governs the world through his Logos with whom he is united from before all time. The Logos became united with humanity through the incarnation into an individual body. This incarnation was real, but Christ did not possess the human weaknesses (such as fear and passion).
The incarnation was the union of the Logos with a human body; the Logos did not assume a human soul. Athanasius attempted to solve the problem of the human soul in the incarnated Logos through inclusions of this human soul and human “psychic” qualities in his definition of the human body.