The Council of Serdica, or Synod of Serdica (also Sardica located in modern-day Sofia, Bulgaria), was a synod convened in 343 at Serdica in the civil diocese of Dacia, by Emperors Constans I, augustus in the West, and Constantius II, augustus in the East. It attempted to resolve the Arian controversy, and was attended by about 170 bishops. It was convened by the two augusti at the request of Pope Julius I.
Background
The first ecumenical council (Nicaea I) canon 5 decreed that bishops should convene in biannual synods within every province to act as a court of second instance and review cases with excommunication sentences pronounced by individual bishops. But, there was no appeal to a court of final instance "if an unjust sentence was imposed" by a provincial synod acting as a court of second instance. Nicaea I canon 5 "implied that" provincial synods "had an acknowledged authority to" judge the acts of individual bishops of their province. Provincial synods' authority "was becoming well established in the East" prior to the council of Serdica. In 341, the Synod of Antioch canons 14 and 15 "were designed both to augment the authority of the provincial synod as a trial court and to ensure the integrity of its operation."
Athanasius of Alexandria was deposed and excommunicated by Eusebians at the first Synod of Tyre (Tyre I) in 335. He was subsequently exiled from Egypt in 339. Thereafter, he appealed the Tyre I sentence to Julius I. Julius I then summoned the Eastern bishops to Rome in 340 to review the Tyre I sentence. Overall, the Eastern bishops rejected the review of the Tyre I sentence and formulated a new creed at the Synod of Antioch in 341. Constans I and Julius I commissioned Bishop Hosius of Cordova, who previously presided over Nicaea I, to preside over the council.
Hosius and other bishops desired final judgments in the cases of Athanasius and other bishops who had been alternately condemned and vindicated by councils in the East and the West. They also desired to definitively settle the confusion arising from the many doctrinal formulas in circulation, and suggested that all such matters should be referred to an ecumenical council. In order to make the council thoroughly representative, Serdica was chosen as the meeting location.
In 340 Athanasius of Alexandria was expelled from his diocese by the Arians. After spending three years in Rome, Athanasius went to Gaul to confer with Hosius. From there, they went to the Council of Serdica, which began in the summer, or, at latest, in the autumn of 343.
Proceedings
Hosius presided over the council of about 170 bishops, of whom about 90 were mostly of the Western Homoousian faction and about 80 were mostly of the Eastern Eusebian faction. It probably convened in 343.
Julius I was represented by the priests Archidamus and Philoxenus, and the deacon Leo. Athanasius reported that bishops attended from Roman diocese of Hispania, Gaul, Britain, Italy, Africa, Egypt, Syria, Thrace and Pannonia. 96 Western bishops attended the council; those from the East were less numerous. Constantius II was represented by Strategius Musonianus and Hesychius of Antioch.
Being in the minority, the Eastern bishops decided to act as a body, and, fearing defections, they all lodged in the same place. On the ground of being unwilling to recognize Athanasius, Marcellus of Ancyra and Asclepas of Gaza, who had been excommunicated in Eastern synods, the Eastern bishops refused to sit in council with the Western bishops. Hosius attempted a compromise by inviting them to privately present their complaints against Athanasius to him, and by promising, in case Athanasius should be acquitted, to take him to Spain. Hosius' overtures failed. The Eastern bishops – although the council had been called expressly for the purpose of re-examining the cases of those who had been excommunicated – defended their conduct on the plea that one council could not revise the decisions of another. Fearing domination of the council by Western bishops, many dissident bishops left the council to hold another, the Council of Philippopolis, where they composed an encyclical and a new creed, which was dated from Serdica.
After the dissident bishops abandoned the council, the bishops who remained at Serdica re-examined the cases of Athanasius, Marcellus, and Asclepas. No new investigation of charges against Athanasius was considered necessary, as these had already been rejected, and he and the other two bishops, who were permitted to present exculpatory documents, were declared innocent. In addition to this, censure was passed on the Eastern bishops for having abandoned the council, and several of them were deposed and excommunicated.