EUSEBIUS of NICOMEDIA. — He was the first bishop of Beirut (Beyrouth), from which around 318 he had himself transferred to the much more important see of Nicomedia, the imperial residence. A master of intrigue, he insinuated himself into the court of Licinius and Constantia, the wife of Constantine. He had been a companion of Arius at the school of Lucian of Antioch and remained his friend. When Alexander of Alexandria condemned the heretic, E. gave him hospitality and took up his defense, provoking Alexander’s protests (Socrates, Hist. eccl., I, 6).
At the Council of Nicomedia a formula of such rigid Arianism was proposed that it was immediately rejected as blasphemous. Finally, he agreed to subscribe to the consubstantial formula. But three months later Constantine exiled him to Gaul. When in 328, at the entreaties of his sister Constantia, he recalled him, he unwittingly provided the anti-Nicene reaction with such a capable and active leader that subsequently the followers of Arius were commonly designated in the sources by the name of “Eusebians.” E. devoted himself for two decades to bringing down the champions of the Nicene Council and rehabilitating Arius. Indeed, in 330 he secured the deposition of Eustathius of Antioch, and in 332 the reconciliation of Arius with Constantine, though not with Athanasius of Alexandria, whom he brought about the condemnation at the Council of Tyre (335). The following year the same fate befell Marcellus of Ancyra. Only the reinstatement of Arius remained. E., unable to obtain his admission into the Church of Alexandria, worked to have him accepted in that of Constantinople, but the heretic died on the eve of triumph. E., however, continued on his path. In May 337 he baptized the dying Constantine at Nicomedia. Thanks also to the priest Constantius, in 338 he obtained, in violation of the prescriptions of the Nicene Council (can. 15), to be installed in the see of Constantinople in place of the bishop Paul, whom he had had deposed. From there he was able to direct the struggle against the Nicene Council with even greater success. He installed in the see of Alexandria a Gregory of Cappadocia, who forced Athanasius to flee to Rome. Pope Julius protested (340). The Council of Encaenia (Antioch, 341), manipulated by E., insolently rejected the protest, denying the Pope’s competence. Shortly afterward, at the end of 341 or early in 342, E. died. Arianism owes to him that it was not immediately extinguished but became a danger to the Church that lasted so long.