Ayres (133-166), Behr (83-95)
A council meets and condemns Photinus, Marcellus, and Athanasius, issuing another reworking of the 4th Antiochene. The focus seems to be the condemnation of Photinus on his home turf. Athanasius responds with his own council in Alexandria.
Aug 10, 353
Magnentius, usurper of Constans in the West, suicides. This, coupled with the execution of Gallus, Caesar in the East, renders the whole empire into the hands of Constantius, providing a unity not seen since Constantine. Constantius, like Constantine before him, will take his universal political scope as an opportunity (for pragmatic reasons) to push for ecclesial and theological unity.
With Constantius in Arles, a small council met, and was presented with the synodal letter from Sirmium. Constantius begins to use this as a tool for uniformity, and presents the ultimatum to either sign up to it or face deposition and exile; all but 2 agree. Ayres notes that Western allegiance to Nicaea emerges as a reaction to Constantius' attempts to enforce conformity to Sirmium. Faced with that choice, opposition begins to form around Nicaea as a rallying standard, and one to which Athanasius himself appeals more and more.
Another council meets in Milan, with the same ultimatum. 3 refuse and are exiled; Hilary also refused, and was exiled as result (Behr, p85, says Hilary was absent and the document was sent to him; Ayres, p137, refers to Synod 91 and affirms that he was present). Also from Milan, Constantius arranged Athanasius' exile, sending troops in Jan 356 who raid his church on the night of Feb 8-9, Athanasius fleeing into the Egyptian wilderness. His replacement, George, arrived in Feb 357 (not popularly received, was almost lynched in Aug 358, and left Oct 2 358.
By Spring 357, Liberius of Rome, previously exiled, was prepared to compromise and sign, and in summer Ossius, last of the die-hards, holed up in Sirmium, also signed. By this time the “blasphemy of Sirmium” contained explicit proscription of ousia language as unscriptural, confusing, and misleading.
It is during this period that Aetius, and his disciple and secretary Eunomius, begin to emerge on the scene. Ayres calls them Heterousians, replacing the traditional ascription 'Anomoians'. Aetius is with George in Egypt in 357, and the two arrive in Antioch where Eudoxius holds a council and endorses the Sirmium Blasphemy.
Basil of Ancyra holds a council before Easter, and aligns the confessions of Constantinople 336, Antioch 341, Serdica and Sirmium 351, presenting the Son as like in essence to the Father. Their position is then presented to Constantius, at that time on the verge of endorsing Eudoxius' position. This Homoian theology wins him over though, and Eudoxius, Aetius, and Eunomius are all exiled. Basil of Ancyra then persuades Constantius to hold firstly a small council, Sirmium 358, which is followed by the twin councils of Ariminum and Seleucia 359
Ariminum and Seleucia 359
Before the twin-council, the small Sirmium council met and drew up the Dated Creed, so named for its explicit date of Pentecost May 22, 359 (Athanasius ridicules their need to date their faith). The creed is vaguely Homoian, and Basil of Ancyra's Homoiousian position is on the decline: he signs with the rider “ not only according to will, but according to hypostasis and according to existence and according to being” whereas Valens wants simply “like the Father” rather than “like in all things”.
The twin councils mark a really special turning point. Ariminum opened May 22, 359 (The dates for both creed and council come from Behr), with 400 bishops or so in attendance. The majority endorsed Nicaea, and felt no need for a new credal statement. Valens, Ursacius, and 80 bishops withdrew from the council, which then formally condemned those two ringleaders. Both groups sent delegations to Constantius, who received the minority first, accepted their position, kept the majority delegation waiting first at Adrianople, then at Niké, and pressured them into accepting the Dated creed, not least by saying the Eastern council had already agreed(!) and by presenting the Dated creed as a reformulation of 'Nicene' theology.
Seleucia opened Sep 27, 359, with 150 bishops initially, and again a majority emerged advocating in their case the Dedication Creed from Antioch. Acacius of Caesarea and his minority withdrew, promulgated their own creed, asserting that the Son was like in will alone. The majority similarly condemned Acacius and his supporters, and both parties sent delegations to Constantius. They met in Constantinople, where Constantius again pressured the majority into accepting the Dated creed, now arguing that Ariminum had already endorsed it (!). A council was held, presided by Acacius, in 360, endorsing this creed, affirming likeness 'according to Scripture', and thus the Imperially backed victory of Homoian theology. They virtually outlawed ousia language, moved decisively away from 'X from X' statements, and left behind the 4th Antiochene. They also deposed a huge number of bishops primarily on conduct grounds. Perversely, many of these were deposed for transferring sees (contra Nicaea 325), and then replaced those bishops with other bishops from various sees (thus breaking the very same Nicene canon). Yet, ironically, the victory of Homoian theology made the Heterousian implications clearer, and drove the Homoiousians away, right at the time that Athanasius was seeking to bring them back to Nicaea.