Alright, settle in for my short guide to a history of the doctrine of the Trinity (with special reference to ecumenical councils).

It’s pretty clear that the documents that later came to comprise the New Testament were formed in a milieu of 2nd Temple Judaism that had, since the return from the Exile, majored on a very distinct and relatively strong version of monotheism. Sure, there was still some variety within that, but monotheism for post-exilic Jews was a distinctive feature, and the emergence of Christianity operates within that milieu. The pattern of treatment of Jesus in the NT corpus as a whole could be described as a form of nascent binitarianism – Jesus is treated as God in a way that does not appear to conflict with earliest believers claim to monotheism. What exactly that means or is meant to look like is unclear on a theoretical level, but more than one passage (I think immediately of Matthew 28:19 and 1 Cor 8:6) co-ordinate the Father and Son, and sometimes Father, Son, Spirit, in ways that would later be called Trinitarian. At the same time, the “Bible” doesn’t mention the Trinity, nor does it attempt to formulate its own doctrine of trinity – primarily because the collection of texts that form the Bible do not have that purpose nor operate anachronistically to answer later believers’ questions and problems like that.

A three-fold pattern of Father, Son, Spirit emerges in early Christian texts and practices, particularly associated with baptism, but also doxology, for example Polycarp prays (Mart.Polycarp 14):

Therefore also I praise You for all things, I bless You, I glorify You, along with the everlasting and heavenly Jesus Christ, your beloved Son, with whom, to You, and the Holy Ghost, be glory both now and forever. Amen.

In the 2nd century a number of authors tried to formulate their understanding of the relationship between these three in more ‘precise’, that is systematic terms. In practice, this is an attempt, as I was trying to explain here, to answer the question of what needs to be the case for the Christian faith and Scriptures to be true as a whole.

Two versions of solutions were advanced that the broader church found problematic at this time: dynamic Monarchianism, associated with Paul of Samosata. Which emphasized God as the sole source and ruler, and understood Jesus to be a human who was adopted and imbued with power at his baptism. This is sometimes called Adoptionism. The other is modalistic Monarchianism, sometimes called Sabellianism, which preserves God’s unity by understanding Father, Son, Spirit to be different modes of being which God exists in sequentially.

These positions in turn provoked ‘orthodox’ responses (orthodox from a later perspective, that is), particularly by Novatian and Tertullian. Tertullian is the one responsible for formulating the use of substantia and trinitas in Latin. Origen, on the other hand, was also active at this time, and was probably one of the most prodigious early Christian thinkers, certainly the most influential of his time.

Fast forward a little bit to the 4th century, and things really get interesting. Early on, around 318, a presbyter in Alexandria called Arius gets upset with the bishop for his teaching that the Son is eternal. Arius’ own theology was not, in the end, that influential. But the clash of Arius and Alexander did occasion a major on-going theological debate that dominated the whole century.

Conveniently (or not), Constantine had rather recently became the dominant Emperor, more or less declared himself a Christian, and already intervened in problems with Donatism (unsuccessfully as it turned out). Constantine’s main motive for getting involved in this dust-up appears to be a strong desire for unity in the church so that the unity would be empire-wide. Hence you have the first ecumenical council at Nicaea in 325. Although, to be fair, it was not really that ecumenical. Attendance by Latin-speaking bishops was low, and it’s very hard to be conclusive that anyone east of the empire turned up. To this point, there had been local councils, but not a really big council like this. Hamilton Hess, in The early development of Canon Law and the Council of Serdica, makes a good case that prior to Nicaea there were various types of church councils, primarily local in nature, and in the 2nd century and 3rd up to circa 250 AD they appear to be more deliberative assemblies. In the second half of the 3rd century they begin to take on more legislative and judicial functions, adopting procedural elements modeled from Roman governance practices. By the early 4th century there was thus a church precedent for councils as deliberative forums that would follow patterns of Roman governance. At the same time there certainly wasn’t a sense of a ‘whole-church’ council that would deliberate and make authoritative pronouncements for the whole church.

So that’s where we get the development of councils from. Nicaea does two things: it effectively deals with Arius’ actual theology by declaring it anathema, and excommunicating Arius. It also writes a creed that appears largely favourable to the formulation of the Father-Son relationship that Alexander backs. (What it doesn’t do is debate the canon of Scripture).

All well and good, and it is true to say that Nicaea 325 played a significant role in the development of the doctrine of the Trinity. But not because (a) it formulated it for the first time, so much as it gave an expression of contemporary theology of it, and not (b) because it gave an authoritative creed, because no-one had the idea of authoritative creeds of that sort at the time.

What it did do is cause a break in the common experience of believers up to this stage and act as a catalyst for a whole body of reflection, writing, polemic, and politics, about the issue of Trinity. Not everyone, it turned out, was happy with Nicaea. So through the rest of the 4th century you get about 4-6 different ‘groups’ advancing various versions of how the Father, Son (and Spirit towards the end) are related and are to be understood, and what it means for Jesus to be ‘God’.

I’ll spare you a full blown narrative of that, because I’m writing one at the moment for my PhD and it’s about 2000 words and too long already.

Let’s fast-forward to 378. Emperor (of the Eastern half) Valens was killed at the battle of Adrianople against the Goths (all his fault really, he should have waited for back-up), and Gratian appoints Theodosius, from Hispania, as emperor of the East. He happens to favour a version of Trinitarian theology that backs the use of Nicaea as its creed, and is opposed to the versions that have been dominant from about 341 through 370 (often called Arianism, neo-Arianism, semi-Arianism, though this terminology is being retired as inaccurate). At the same time the theological currents have shifted, and so Theodosius (a) issues a decree Cunctos populous that makes Nicene Trinitarianism as defined by the current positions of the bishops of Rome (Damasus) and Alexandria (Peter), the Imperial and Catholic position. This, not Constantine, is the moment when Christianity becomes an Imperial and State religion. (b) he also summons a new council, Constantinople 381, which reformulates the creed from Niceae and issues a ‘revised’ version, which more or less settles the issue within the Empire. This creed is often called the Nicene creed, but it is more correctly called the Niceno-Constantinopolitan creed (but that’s a mouthful).

by this point, classical Trinitarian theology is fairly stable. It has sorted out a terminology, that God exists as one essence/nature (οὐσία in the Gk), in three persons (ὑπόστασις (sg) in the Greek), that Father and Son exist in eternal relation as eternal Father of a generated but equally eternal Son, that similarly the Spirit exists in eternal relation of procession from the Father (and maybe from the Son – that’s the filioque issue).

Not a lot happens with the Trinity from a conciliar point from this point on. Issues in the 5th century tend to move on to how to understand the humanity and divinity within Jesus, and ‘Trinity’ is more or less settled.

Let’s fast-forward again to talk about the Reformation. Protestants generally share the same fundamental doctrine of Trinity as Catholic and Orthodox churches do. The main interest of Protestant reformers in the Trinity was to relate the doctrine of trinity to their (reform-ed/ing) views of how salvation works. You see this not so much in the first generation of reformers, but developments in scholastic Calvinism, etc., and the emergence of a ‘covenant of redemption’ within the Godhead and such things. But no, Protestants don’t do much with the doctrine of Trinity in terms of reformulating or altering it, they’re generally happy with it as is.

Okay, history of Trinity 101 is over, now taking questions.