The best part of the 4th Century of Christianity was the intervening years between 325 and 381. Here, Roman almost slipped back into Paganism at the most and a pluralistic society as the least:
Constantius called the council of Sirmium. It was held by the Court Bishops (Heteroousios) and the Homoeousians. The results were a compromise in which the subordinatist tendencies were toned down. It attempt to forbid the use of the word ‘ousia.’ This synod was unofficial, and only as a preparation to a desired Ecumenical Council.
Two Councils were called, East and West, to work on a harmonization. The Emperor worked behind the scenes in securing the compromise. The Western Council denied the doctrine of the one Hypostasis but a passing reference was given to the ‘likeness’ of the Father and the Son. Both councils were adjourned to meet in Constantinople. The final creed still forbade the use of ousia as well as the Western Monarchian language by forbidding the use of the word hypostasis. This created a new group, the Homoeans (Father and Son similar)
All Bishops who did not recognize it were removed from the Sees by the Imperial Court.
On the way to stop a rebellion by his cousin, Julian, Constantius died, leaving Julian as the Emperor.
Julian adopted Paganism and refused to be involved in the Church’s disputes. He sought to restore religious plurality. He did, however, seek to destroy Christianity by allowed all the bishops that had been banished to return to their Sees, even where other bishops already occupied the offices. He thought that the civil war that would ensue would hasten the downfall of Christianity. In 362, he recalled all Bishops, including Athanasius; however, Athanasius Homoean opponent, George, had been lynched the previous year.
To prevent Julian’s hoped for war, Athanasius as well as Liberius in Rome, allowed full communion to all who accepted Nicaea and rejected Arianism. In the same year, Athanasus called a Synod which affirmed his theology but called for the inclusion of other theologies. He attempted a compromise with the Homoeans, led by Euzious (Arius’ former Deacon) and the Old Nicene community lead by Paulinus. A group that advocated the Easter doctrine of three hypostaseis formed around Meletius of Antioch. Both Paulinus and Meletius sent delegates to Alexandra.
Athanasius conditioned communion on rejection of Arius, recognition of Nicaea, and the condemnation of the rising view that the Spirit was of a different ousia than of Christ.
Athanasius, who had supported Serdica in 342 and who, along with Marcellus of Ancrya, helped to draft the miahypostatic language of that council, called the formula and doctrine as pronounced there, as superfluous and non-binding, to curry favor with the Meletians. He distanced himself from Marcellus.
In a compromise to the Meletians, Athanasius abandoned the maihypostatic doctrine of his youth in favor of a new understanding of hypostasis. He persuaded the miahypostatics of the Old Nicenes to abandon their ‘modalistic’ tendencies in favor of the new understanding of Nicaea. These negioations were set down in the ‘Tome to the Antiochenes’ (362). The Tome allowed that the Ousia and Hypostasis held the same meaning. Further, the issue of three or one was not to be pressed because the terms were now equated.
The compromise was held up by the personal battle between Athanasius and Meletius. Lucifer of Calaris a deposed bishop under Constantius ordained Paulinus as Bishop of Antioch, displacing Meletius. Because Paulinus signed the letter, Meletius and his faction refused to follow it.
Later in 362, Julian banished Athanasius, causing the bishop to feel. The emperor would soon loose his life the following year. Jovian, a Christian General, assumed the imperial throne.
Jovian refused to bow to pressure and did not banish bishops.
Meletius assembled a synod to proclaim the Nicene Faith. The Eastern Bishops, because of the flair ups of Arianism, was pushed to accepting, politely, the Nicene Creed, and building their theology around it. Before anything substantial could be developed, Jovian died, leaving the Empire divided between Valentinian (West) and Valens (East). Valens restored the dogma of the Homoeans, returning the East to pre-361. He did not have the power of Constantius and had to allowed Athanasius to return to Alexandra in 366, where he retained power until his death in 373.
In the early 370’s Valens banished Meletius, but his community survived by adopting more pro-Nicene theology, due to the leadership of the Cappadocian Fathers.