pope from 337 to 352. The papacy had been vacant four months when he was elected as St. Mark's successor on Feb. 6, 337. Julius then became the chief support of orthodoxy and the Nicene Creed against Arianism, a heresy that held Christ to have been human, not divine.

In 339 he gave refuge at Rome to Bishop St. Athanasius (Athanasius, Saint) the Great of Alexandria, who had been deposed and expelled from his see by the Arians. At the Council of Rome in 340, Julius reaffirmed Athanasius' position. Julius then tried to unite the Western bishops against Arianism by convoking in 342/343 the Council of Sardica (now Sofia, Bulg.). The council acknowledged the pope's supreme authority, enhancing his power in ecclesiastical affairs by granting him the right to judge cases of legal possession of episcopal sees. Thus Julius restored Athanasius and refuted all Arian charges; his decision was confirmed by the Roman emperor Constantius II (an Arian) at Antioch. Julius' letters are preserved in Athanasius' Apology Against the Arians.