Arianism is the theological teaching attributed to Arius (ca. AD 250-336), a Christian presbyter in Alexandria, Egypt, concerning the relationship of God to the Son of God (Jesus of Nazareth). Arius asserted that the Son of God was a subordinate entity to God the Father. Deemed a heretic by the Ecumenical First Council of Nicaea of 325, Arius was later exonerated in 335 at the regional First Synod of Tyre, and then, after his death, pronounced a heretic again at the Ecumenical First Council of Constantinople of 381. Athanasius of Alexandria (b. ca. 296-298 - d. 2 May 373), also referred to as St. Athanasius the Great, St. Athanasius I of Alexandria, St Athanasius the Confessor and (primarily in the Coptic Orthodox Church) St Athanasius the Apostolic, was the 20th bishop of Alexandria. His episcopate lasted 45 years (c. 8 June 328 - 2 May 373), of which over 17 were spent in five exiles ordered by four different Roman emperors. He is considered to be a renowned Christian theologian, a Church Father, the chief defender of Trinitarianism against Arianism, and a noted Egyptian leader of the fourth century.