(Ἀέτιος), surnamed the Atheist, from his denial of the God of Revelation (St. Athanas. de Synod. § 6, p. 83, of the translation, Oxf. 1842 ; Socr. Hist. Eccl. 2.35; Sozom. Hist. Eccl. 4.29), was born in Coele Syria (Philostorg. Hist. Eccl. 3.15; St. Basil, ad v. Eunom. i. p. 10) at Antioch (Soc. 2.35; * After the first reference, the references in this article are thus abbreviated :-- St. Athanasius, de Synodis [S. Ath.]; St. Basil, adv. Eunomianos [S. Bas.]; St. Gregory Nazianzen adv. Eunomian. [S. Gr.] The Histories of Socrates, Sozomen, Theodoret, and Philostorgius, the Arian panegyrist of Aetius [Soc., Soz., Thdt., Phil.]; S. Epiphanius, adv. Haereses [S. Ep.]. Suidas, s. v. Ἀέτιος), and became the founder of the Anomnoean (ἀνόμοιον) form of the Arian heresy. He was left fatherless and in poverty when a child, and became the slave of a vine-dresser's wife (St. Gregory Nazianz. c. Eunom. p. 292, C. D; but see Not. Vialesii ad Philost. 3.15), then a travelling tinker (S. Gr. ibid.) or a goldsmith. (Phil. ibid.) Conviction in a fraud or h ambition led him to abandon this life, and he applied himself to medicine under a quack, and soon set up for himself at Antioch. (Soc. 3.15.) From the schools of medicine being Arian, he acquired a leaning towards heresy. He frequented the disputatious meetings of the physicians (S. Gr. p. 293, D) and made such progress in Eristicism, that he became a paid advocate for such as wished their own theories exhibited most advantageously. On his mother's death he studied under Paulinus H., Arian Bishop of Antioch, A. D. 331; but his powers of disputation having exasperated some influential persons about Eulalius, the successor of Paulinus, he was obliged to quit Antioch for Anazarbus, where he resumed the trade of a goldsmith, A. D. 331. (Phil. 3.15.) Here a professor of grammar noticed him, employed him as a servant, and instructed him; but he was dismissed in disgrace on publicly disputing against his master's interpretation of the Scripture. The Arian Bishop of the city, named Athanasius, received him and read with him the Afterwards he read the with Antonius, a priest of Tarsus till the promotion of the latter to the Episcopate, when he returned to Antioch and studied the Prophets with the priest Leontius. His obtrusive irreligion obliged him again to quit Antioch, and he took refuge in Cilicia (before A. D. 348), where he was defeated in argument by some of the grossest (Borborian) Gnostics. He returned to Antioch, but soon left it for Alexandria, being led thither by the fame of the Manichee Aphthonius, against whom he recovered the fame disputation which he had lately lost. He now rezsumed the study of medicine under Sopolis and practised gratuitously, earning money by following his former trade by night (Phil. 3.15) or living upon others. (Theodoret, Hist. Eccl. 2.23.) His chief employment, however, was an irreverent application of logical figures and geometrical diagrams to the Nature of the Word of God. (S. Epiphan. ad v. Hacres. § 2, and comp. § 6, p. 920.) He returned to Antioch on the elevation of his former master Leontius to that See, A. D. 348, and was by him ordained Deacon (S. Ath. § 38, transl. p. 136), though he declined the ordinary duties of the Diaconate and accepted that of teaching, A. D. 350. (Phil. 3.17.) The Catholic laymen, Diodorus and Flavian, protested against this ordination, and Leontius was obliged to depose him. (Thdt. 2.19.) His dispute with Basil of Ancyra, A. D. 351 (fin.), is the first indication of the future schism in the Arian heresy. (Phil. 3.15.) Basil incensed Gallus (who became Caesar, March, A. D. 351) against Aetius, and Leontius' intercession only saved the latter from death. Soon Theophilus Blemmys introduced him to Gallus (S. Gr. p. 294), who made him his friend, and often sent him to his brother Julian when in danger of apostacy. (Phil. 3.17.) There is a letter from Gallus extant, congratulating Julian on his adesion to Christianity, as he had heard from Aetius. (Post Epist. Juliani, p. 158, ed. Boisson. Mogunt. 1828.) Aetius was implicated in the murder of Domitian and Montius (see Gibbon, c. 19), A. D. 354 (S. Gr. p. 294, B), but his insignificance saved him from the vengeance of Constantius. However, he quitted Antioch for Alexandria, where St. Athanasius was maintaining Christianity against Arianism, and in A. D. 355 acted as Deacon under George of Cappadocia, the violent interloper into the See of St. Athanasius. (St. Ep. 76.1; Thdt. 2.24.) Here Eunomius became his pupil (Phil. 3.20) and amanuensis. (Soc. 2.35.) He is said by Philostorgius (3.19) to have refused ordination to the Episcopate, because Serras and Secundus, who made the offer, had mixed with the Catholics; in A. D. 358, when Eudoxius became bishop of Antioch (Thdt. 2.23), he returned to that city, but popular feeling prevented Eudoxius from allowing him to act as Deacon.

The Aetian (Eunomian, see ARIUS) schism now begins to develop itself. The bold irreligion of Aetius leads a section of Arians (whom we may call here Anti-Aetians) to accuse his to Constantius (Soz. 4.13); they allege also his connexion with (Gallus, and press the emperor to summon a general Council for the settlement of the Theological question. The Aetian interest with Eusebius (Soz. 1.16), the powerful Eunuch, divides the intended council, but notwithstanding, the Aetians are defeated at Seleucia, A. D. 359, and, dissolving the council, hasten to Constantius, at Constantinople, to secure his protection against their opponents. (S. Ath. transl. pp. 73, 77, 88, 163, 164.) The Anti-Aetians (who are in fact the more respectable Semi-Arians, see ARIUS) follow, and charge their opponents with maintaining a Difference in Substance (ἑτεροούσιον) in the Trinity, producing a paper to that effect. A new schism ensues among the Aetians, and Aetius is abandoned by his friends (called Eusebians or Acacians, see ARIUS) and banished (S. Bas. 1.4), after protesting against his companions, who, holding the same principle with himself (viz. that the Son was a creature, κτίσμα), refused to acknowledge the necessary inference (viz. that He is of unlike substance to the Father, άνόμοιον). (Thdt. 2.23; Soz. 4.23; S. Greg. p. 301, D. ; Phil. 4.12.) His late friends would not let him remain at Mopsuuestia, where he was kindly received by Auxentius, the Bishop there : Acacins procures his banishment to Amblada in Pisidia (Phil. 5.1), where he composed his 300 blasphemies, captious inferences from the symbol of his irreligion, viz. that Ingenerateness (ἀγεννησία) is the essence (οὐσια) of Deity; which are refuted (those at least which St. Epiphanius had seen) in S. Ep. ad v. Haer. 76. He there calls his opponents Chronites, i.e. Temporals, with an apparent allusion to their courtly obsequiousness. (Praefat. apud S. Ep.; comp. c. 4.)

On Constantius's death, Julian recalled the various exiled bishops, as well as Aetius, whom he invited to his court (Ep. Juliani, 31, p. 52, ed. Boisson.), giving him, too, a farm in Lesbos. (Phil. 9.4.) Euzoius, heretical Bishop of Antioch, took off the ecclesiastical condemnation front Aetius (Phil. 7.5), and he was made Bishop at Constantinople. (S. Ep. 76. p. 992c.) He spreads his heresy by fixing a bishop of his own irreligion at Constantinople (Phil. 8.2) and by missionaries, till the death of Jovin, A. D. 364. Valens, however, took part with Eudoxius, the Acacian Bishop of Constantinople, and Aetius retired to Lesbos, where he narrowly escaped death at the hands of the governor, placed there by Procopius in his revolt against Valens, A. D. 365, 366. (See Gibbon. ch. 19.) Again he took refuge in Constantinople, but was driven thence by his former friends. In vain he applied for protection to Eudoxius, now at Marcianople with Valens; and in A. D. 367 (Phil. 9.7) he died, it seems, at Constantinople, unpitied by any but the equally irreligious Eunomius, who buried him. (Phil. 9.6.) The doctrinal errors of Aetius are stated historically in the article on ARIUS. From the Manichees he seems to have learned his licentious morals, which appeared in the most shocking Solifianism, and which he grounded on a Gnostic interpretation of St. John, 17.3. He denied, like most other heretics, the necessity of fasting and self-mortification. (S. Ep. ad v. Haer. 76.4.) At some time or other he was a disciple of Eusebius of Sebaste. (S. Bas. Epist. 223 [79] and 244 [82].) Socrates (2.35) speaks of several letters from him to Constantine and others. His Treatise is to be found ap. S. Epiphan. ad v. Haer. 76, p. 924, ed. Petav. Colon. 1682.