This is just an overview of the beginning of the movement in the church to have general councils without addressing how they compare to original Christianity.
325 AD marks the year of the beginning of this movement in the Church, the great General Councils of the church. It marks Nicea I as the first general council since Jerusalem around 50 AD.
Interestingly, the eight general councils from Nicea I to Constantinople 3 are considered as a unit in the development of the church. The reason for this is because they are considered to be a series of meetings from which the essential Christian doctrine was developed. They are also considered to be a unit because, despite the decrees issued at each one, the issues being discussed were never fully resolved as new questions and issues arose with each decree. The task of these councils was to “hammer out in words the central mysteries of Jesus’ humanity and divinity, of the Trinity’s essence, and Mary’s relationship to Jesus as God and human being.”
These councils are the story of how the above doctrines were decided, became so precisely defined, and became so dominant.
The problem was that the precise nature of our Lord Jesus Christ was not agreed upon, and this lack of unity meant that there was not one church with one body of doctrine that the Empire could call Christianity. The councils began with the mission to resolve that problem. It was decided to develop the doctrine to decide on clear answers.
These first eight councils span about 355 years to resolve these issues above. No matter how clear the decrees were from each Council obstacles arose after each one. In fact, some of the decrees were completely reversed, and even re-reversed. For example, after Arius was condemned as a heretic for not agreeing that Jesus was co-equal with the Father, there were groups that praised him as a hero, and his opponent, Athanasius, was exiled a number of times from his bishopric as these reversals happened.
It is important to note that opposed to the first council at Jerusalem there were no prophets and apostles attending the General Councils as those offices were considered replaced by bishops in Catholic doctrine. The emperor often convened the council while the Roman empire was in power. Bishops presented theological arguments. Theological concepts down to precise vocabulary were battled over until a precisely worded decree might be issued. And if it was issued, it would also be declared that it was anathema to speak or even think against it. Yet, the disputes continued, and decrees were even sometimes reversed. That is the legacy of the first General Councils, especially in the first millennium.
It is important to note that this process was started by none other than Constantine the Emperor himself as he called the Empire’s bishops together at Nicea I where he led with a strong hand. Whereas later canon law now dictates that only a Pope can convene a council, the Pope at that time, Sylvester 1, didn’t even attend the council although he did send representatives. This set a precedent that continued at many of the councils in the first millennium. The head of the government, not the bishops, called and ran much of the councils. 
It must also be noted that Constantine by 325 A.D. was decidedly Christian, but it had been a slow process. As Emperor his concern was the unifying of the Empire and that included religious unification. Previously, it had been the policy where all gods (plural) were to be acceptable in the Empire. (Christianity was illegal because it didn’t allow for other gods.) There’s not a lot written about Constantine’s Christianity before 325 A.D. other than he appears to be have been making stormy progress towards Christianity. He’s described as “passionate, turbulent, and superstitious”, and he had professed allegiance to the sun God up until about 323 A.D, hardly making him an experienced Christian theological scholar.
This new dynamic of Christian acceptance, however, was a radical departure from the first centuries of Roman rule where the Emperor and his government persecuted Christians. And the result was that Christians were able to live their lives without persecution. And that was celebrated.
Of particular note at Nicea I, is the use of a non-biblical Latin word, homosousias, in Athanasius’s statement defining the nature of our Lord. Homosousias means “of the same substance”. This word, not found in the Bible, was used to establish that Jesus is coequal with his Father and co-eternal with him. Also, part of the logic given with that was that if only God could save human beings and Jesus isn’t God, then Jesus didn’t save human beings. The finest theological minds in the empire presented their arguments, and a decision was made. Anyone disagreeing at that point was declared a heretic. The majority held that Athanasius was right. The very powerful emperor was impressed with Athanasius’ argument also. Arius and the minority of bishops disagreeing with Athanasius were declared heretical.
Despite what is written in some historical accounts, Nicea I church fathers “had only said that they believed in the Holy Spirit, without applying any of the language used to describe the Father’s relationship with the Son to the Spirit.” So, no, the doctrine of the Trinity was not developed at Nicea. (It wouldn’t be until Constantinople I where they defined the Spirit as “proceeding forth from the Father, co-worshiped and co-glorified with the Father and Son.”)
Theological language, vocabulary, and logic were at the center of the issue. Also, western bishops spoke mainly Latin while Eastern bishops spoke mainly Greek and there isn’t always a one-to-one correspondence in translation to boot.
Again, Nicea I didn’t really resolve the issue of who Christ was exactly. The Arian camp still had followers and started promoting the words “homoios” which means “like the father” and “homoi-ousios” also indicating Jesus was like the Father to combat the Athanasian term that was so well received. Then, after Constantine, the empire was divided among his three sons. The sons allowed the exiled bishops to return. At one point, an Arian bishop, Gregory of Cappadocia, was installed in Alexandria in place of the now exiled Athanasius. This was quite the political quagmire because the empire was now divided under different emperors and the different factions were divided over the Arian controversy. From this, we see that this issue was so important and had to be decided, as far as the Empire was concerned, because the dispute was part of what was destabilizing the Empire.
As a result, the next council, Constantinople I, picked right up again on the controversy. One major effort of that council was to reestablish the Nicene creed as the official creed of the church. According to Belitto, the concept of the holy spirit was advanced closer to the concept of “Homo-ousios”, of one substance with the father, but was not identified at that point as on the level of the Father and the Son.
Walker in his work describes the issue as intellectual with the ultimate Nicene victory as an “intellectual victory.”
The next council was at Ephesus. After Constantinople I, the Bishop of Constantinople, Nestorius tried to reconcile the resulting questions of how the human and divine natures worked. After all, now Jesus is both God and man. And how does that work with his mother, Mary? Nestorius said that Mary was the mother of the human Jesus, but not the mother of God. Cyril of Alexandria disputed that view saying that made Mary only the mother of half a person. The Council at Ephesus condemned Nestorius calling him “a new Judas”.
Cyril had made his proclamation, however, without any of the Eastern bishops or the Pope’s delegates attending. The Eastern bishops turned around and condemned Cyril. Then the Pope’s delegates came and nullified both councils with their proclamations.
Negotiations continued over the next two years. The result of the negotiations was a proclamation condemning Nestorius again. In the proclamation, Mary was for the first time recognized as the “theotokos”, the mother of God as Jesus’ divine nature and human nature still only represented one person.
Statement by statement these doctrines were developed. For example, the proclamation also declared that it was Jesus’ human nature that suffered, but that his divine nature could not suffer. And the Ephesus Council developed the concept of the “hypostatic union” by which Jesus is human and divine natures were fused into one person.
Look at this carefully worded result:
“… We do not say that the nature of the word was changed and became flesh, nor that he was turned into a whole man made of body and soul. Rather do we claim that the Word in an unspeakable, inconceivable manner united to himself hypostatically flesh enlivened by a rational soul, and so became man and was called son of man, not by God’s will alone or good pleasure, nor by the assumption of a person alone. Rather did two different natures come together to form a unity, and from both arose one Christ, one Son. It was not as though the distinctness of the natures was destroyed by this union, but divinity and humanity together made perfect for us one Lord and one Christ, together marvelously and mysteriously combining to form a unity.”
The Council of Chalcedon in 451AD further refined the delicately worded concepts of who Christ is in his humanity and divinity.
“… We all with one voice teach the confession of one and the same son, our Lord Jesus Christ: the same perfect in divinity and perfect in humanity, the same truly God and truly man of a rational soul and a body; consubstantial with the father as regards his divinity, and the same consubstantial with us as regards his humanity; like us in all respects except for sin; begotten before the ages from the father as regards his divinity, and in the last days the same for us and for our salvation from Mary, the Virgin God bearer, as regards his humanity; one and the same Christ, Son, Lord, only begotten, acknowledged into natures which undergo no confusion, no change, no division, no separation; at no point was the difference between the two natures taken away through the union, but rather the property of both natures is preserved and comes together into a single person in a single subsistent being; he is not parted were divided into two persons, but is one in the same only begotten son, God, word, or Jesus Christ…”
And as other councils the Chalcedon Council participants thought that their work was done, and issued a statement like other councils that it was forbidden to even think other than what the council declared:
“Since we have formulated these things with all possible accuracy and attention, the sacred and universal synod decreed that no one is permitted to produce, or even to write down or compose, any other creed or to think or to teach otherwise.”
The next council really shows a lot of how integrated politics, government, and church doctrine were in these days of the church councils. The Council of Constantinople II was called by Emperor Justinian. Amazingly, Justinian’s wife, Empress Theodora, had favored Monophysitism, and even helped get the Vigilius elected pope in hopes of reversing Chalcedon! Monophysitism is one of the doctrines that had been labeled a heresy in these discussions in previous councils. It basically states that Jesus just really just had a divine nature, but there was still a strong contingent for it. Again, the emperor, not the pope, convened the council. Again, the pope did not attend, and Justinian reconfirmed the previous doctrine of the hypostatic union of two natures in one person. Also, numerous condemnations were issued about both people and doctrines. But the pope refused to comply! This initiated a standoff between the Emperor and the Pope. As usual, the emperor prevailed and the pope backed down.
The issues evolved but the councils continued in a similar fashion. There were a lot of politics as especially in the first millennium the emperor often ran the Council which consisted of a lot of hammering out concepts not precisely defined in the scripture down to precisely defining the meaning of words. With those decrees came more decrees that if you didn’t agree with them, you became a heretic. This shows the workings of the Churches’ development of doctrine through the Councils for many centuries. There are 21 General Councils overall and this brief overview shows the nature of them, especially of the first millennium. General Councils have continued in the Roman Catholic Church until Vatican II in 1965.
More will be covered on this movement in future articles,
 THE GENERAL COUNCILS, Christopher M Bellitto, Paulist Press, New York, 2002, P. 15
 Ibid, p. 19
 Ibid, p.18
 THE RISE OF CHRISTIANITY, W.H.C. Frend, Fortress Press, Philadelphia, 1984, P. 484
 THE GENERAL COUNCILS, p.21
 A HISTORY OF THE CHRISTIAN CHURCH, Williston Walker, Scribner, New York, 1959. P.113-114
 THE GENERAL COUNCILS, p.21
 A HISTORY OF THE CHRISTIAN CHURCH, P.117
 THE GENERAL COUNCILS, p.23
 ibid., P. 24
 Ibid, p.26