It always astonishes me that my students are astonished at the development of Christian doctrine. These innocents, knowing very little even recent American history, know absolutely nothing about ancient Christian history. They seem fondly to have imagined—if they have thought about the matter at all—that, e.g., the Nicene Creed “had fallen from heaven quite unexpectedly during Good Friday luncheon some years back” (to use one of the lines from Evelyn Waugh’s uproariously politically incorrect novel Black Mischief). When they discover that it did not—that the creed was a lengthy process of synodal or conciliar debate going on for decades—they are not only amazed but some of them even a little disgusted. The raw humanity of the Church--which, I must remind them, has two natures, as Christ did: divine and human--seems to be rather disdainful to some. (Others, of course, can see only the human side, and therefore reductionistically and simplistically assume that every decision was the result always and only of political machinations of the most sordid and self-interested variety, with no possible room for the Holy Spirit to drop His ready-made creeds into the diners' laps.)
When we cover the era of The First Seven Ecumenical Councils (325-787): Their History and Theology, starting at Nicaea I in 325 and ending with Nicaea II in 787, and spending the most time on Chalcedon in 451, every one of them in classes going back nearly a decade has professed to be amazed at how messy, protracted, polemical, and confrontational the process was by which Christological doctrine was shaped and defined, not least in the creed. In the passive-aggressive argot of today, they ask: Why was everyone so “divisive”? Wasn’t the reaction to Arius rather “extreme”? Couldn’t they have just tolerated a diversity of opinions?
After all, who cares how many natures Christ has, or what the relationship, if any, between them is. This is all irrelevant nonsense--isn't it? We can still be nice persons whether Christ has one nature, two, or 391,704.
Eventually, of course, the Church was guided to understand the dyophysite nature of Christ, and to settle other related and controverted matters. But it took time and effort lasting centuries. There was, then, no neat, tidy, simple, quick process for the formation of doctrinal claims that most of us take for granted today and have seemed settled for ages if not forever. It was a process taking decades and centuries, and in the meantime there was a lot of unsettled opinion and a great deal of vigorous, and occasionally violent, fighting. A very good, if dense, book for the formation of Christological doctrine remains that of Khaled Anatolios (whom I interviewed here), Retrieving Nicaea: The Development and Meaning of Trinitarian Doctrine.
Such is the way of synods and councils, East and West, ancient and modern. As we finish the seemingly endless commemorations of Vatican II this year, Catholics of a certain age--now fewer and fewer with each passing year--will remember the tumult in the post-conciliar period. Those with longer historical memories will know that whether it is Nicaea I, Chalcedon, Lateran IV, Trent, or some other synod, it takes decades for things to settle down, and in the meantime the process remains often painfully messy. Indeed, in not a few cases, things get worse after a synod/council, and the question is often raised: was the "cure" not worse than whatever the precipitating "disease" was? Such is the way synodality down through the ages.
I mention all this in anticipation of what I fully expect to be a shambolic synod in Rome in October, picking up where last year's session left off. I've talked to many people who have been disconcerted by the messiness and controversy last fall, but such concern is, in part, likely a function of just how unfamiliar the West is with synodality, though there is a long history of the same going back to the earliest centuries, as I documented in my book, Orthodoxy and the Roman Papacy: Ut Unum Sint and the Prospects of East-West Unity.
For those wishing more depth and detail on the topic, see the hefty scholarly collection (of uneven quality, and with articles in French and other European languages), Synod and Synodality: Theology, History, Canon Law and Ecumenism in New Contact.
Other works, most of them mentioned or reviewed on here over the years, that may be of interest would include Paul Valliere's rather uneven but still insightful Conciliarism: A History of Decision-Making in the Church.
Valliere's title does not really treat what one expects under the heading of "conciliarism," on whose history, in the West, Francis Oakley is the doyen. As I have noted before, Oakley's book on the topic, The Conciliarist Tradition: Constitutionalism in the Catholic Church 1300-1870, discussed in depth here, is a deeply disturbing one raising age-old questions that nobody has bothered to answer--preferring instead to ignore them or "forget" them. I am using part of it in a lecture I am giving at Fordham next month at the OTSA meeting.
Finally, I would recommend a rich collection discussing ecclesiological and ecumenical issues, including synodality: Receptive Ecumenism and the Call to Catholic Learning: Exploring a Way for Contemporary Ecumenism.