Reading up about the first seven Ecumenical Councils (particularly at the first Nicaean and the first two Constantinopolitan councils) the status of the Arian belief system seems to crop up again and again as a subject of great importance to Pentarchy.
From what I understand and feel free to correct me), Arian Christians were concerned with the nature of Christ. They rejected the belief that Christ was one with God and the Holy Spirit, believing instead that he was created by God.
What was it about these teachings that so inflamed and preoccupied the church? As a modern reader looking back on the issue, I don't quite grasp why it was seen as such a challenge to the status-quo.
(Full disclosure, I harvested some of this answer from my own previous answers on the topic.)
So the Arian conflict gets going around 318. Arius, presbyter in Alexandria, hears a sermon by Alexander (bishop) of Alexandria, who is teaching that the Son (= Jesus, the second Person of the Trinity) is eternal. Arius gets very worked up about this, because in his view, this teaching amounts to saying that the Father and the Son are two uncaused, eternal principles in the universe, i.e. two ultimate “Gods”, and this is polytheism. Arius protests about Alexander’s theology, and Arius’ beliefs become apparent in his writings and teaching – Arius believes that the Son is a created entity, that he is distinct from God in nature, but that he is still ‘god’ (it’s very helpful to realise that our concept of a strict division between God and Everything else is in part an outworking of the Arian controversies); he is perfect, and he is the perfect model of how to be saved.
Alexander holds a local council and has Arius deposed. Arius and his followers head up into Palestine, and Arius starts trying to garner support for his position. He is somewhat successful. Alexander is called to account for his actions. Alexander calls on other bishops in the empire for support. All this eventually makes its way to Constantine I.
Now, Constantine hasn’t been sole emperor very long, but he’s drawn into theological disputes very quickly. And he is interested, because he wants unity in the empire, and unity in the church. Can’t we all just get along and figure this out? He’s advised primarily by Osius of Cordoba. Constantine decides, hey let’s have a big council and sort this Arius business out. So a small council meets preliminarily in Antioch in 325, and then we have the big council of Nicaea later in 325.
It really was the first council of its size or kind. Its main concern was to deal with Arius and his theology. The majority of the church rejected Arius’ theology as a departure from the historic Christian faith, considering that Jesus = creature to be heretical. Arius is exiled, and despite attempts at bringing him back never really gets much traction for himself and his teaching. ‘Arianism’ proper dies a quick death.
Except that no-one was really happy at Nicaea except maybe for Alexander and his secretary Athanasius. Athanasius becomes Alexander’s successor in Alexandria (328), and promotes a theology that is what we’ll call “pro-Nicene”. That is, Athanasius sees the trinity and the relationship between God as Father and Son as one of distinction, but with oneness of essence. The key word is homoousios, of the same substance, which is used in the Nicene creed to reject Arius’ teachings that Christ and God are of different substance/essence/being.
But most of the other Eastern bishops don’t really agree with Athanasius’ theology, and aren’t really happy with the Creed they produced. They generally thing that (a) homoousios language goes to far and smacks of modalism (a view that God is just absolutely one, and only appears in different forms at different times. i.e. that he was the Father, and then he is the Son, and then he is the Spirit), or some form of that, (b) that the relationship between Father and Son is one of some kind of likeness but not identity. So in the aftermath of Nicaea, Athanasius starts to go head to head with pretty much the rest of the East church, and later emperors are not so fond of him, so he gets exiled repeatedly. Importantly Athanasius ends up in Rome, where they are much more sympathetic to him, and he meets up with Marcellus of Ancyra. Marcellus has his own pretty distinct theology, which while it also favours Nicene-language, is much more like the modalism that all the Easterns are worried about. Anyway, Athanasius learns a neat trick from Marcellus – if you call your opponents ‘Arians’ it makes them look really bad, even if they’re theology doesn’t derive from Arius himself. So Athanasius casts the debate in this way, and historical readings of it up until the last 20 years have been dominated by this langauge (including various shades of ‘semi-Arianism’.
Once you get into the 350s, most of the momentum has shifted to these Eastern bishops, and the Emperors who are generally more interested in political unity within the church. The dominant position has become known to us as homoiousionism, i.e. ‘like in substance’ but not identical. This is kind of a have-your-cake-and-eat-it-too theology, where the Father and Son are similar, but not the same. The debate through this period is a lot about how to reconcile scriptural texts that talk about Father and Son being equal, and Father and Son being in hierarchy. The Easterns say they have a unity of will, but are different in essence. While those favouring Nicene language maintain that there is unity of essence, and the passages about hierarchy/distinction are more about the Son’s role during his coming to earth, dying on the Cross, saving humanity.
I’m simplifying a lot; let’s push on. In the 360s and 370s you see a new generation of theological thinkers take up the task. Especially you see three guys in the East who get along really well, we like to call the the Cappadocians, because that’s where they’re from. And you get Hilary of Poitiers in the West. These guys in one way carry on Athanasius’ work, but in another way they don’t, since their writings show a distinct lack of direct influence. At this time the other side of the debate is getting into more extreme territory. So Homoiousians develop two splinter groups, the first get labelled Homoians, they basically just want to say “The Son is kind of like the Father, but we’re not sure how and let’s not really talk about it”. They become a dominant political faction from around 357 onwards (The Sirmium Council). Then you get a group we call Heteroousians, who just go all out and say the Father and Son share nothing in common, they are completely different.
In 360 there’s a council at Constantinople that looks like everything is coming up roses for the Homoians. They’ve got imperial backing, they’ve got a creed they like, they seem to be dominating the church. But it’s an illusory victory – the push for some towards Heteroousianism is pushing more moderate bishops to think that homoiousios is actually close enough to look like homoousios, and so move back to the Nicene position.
Meanwhile, the Cappadocians turn up. That’s Gregory of Nazianzus, Gregory of Nyssa, and Basil of Caesarea. These guys are power-houses of theological genius. They’ve had top-class education in rhetoric and philosophy, are very into theology, and they start to do some heavy mental lifting. hey pitch several arguments that basically say – hey, look where these crazy guys are taking your theology. If the Son is like in esssence to the Father, that pretty much means he is the same in essence. So let’s stick with the language from good ol’ Nicaea.
The other important thing they do is the take two Greek words for ‘essence’, ousia and hypostasis and start to use them differently, to provide a new vocabulary for talking about God as one ousia, but three hypostaseis (this is mirrored in English by one in essence, three in person, but we have shifted our meaning of ‘person’ from the Latin).
Anyway, this sways a bunch of moderates. The other happy coincidence is that Theodosius I becomes Emperor, and he’s from the West and very much pro-Nicene. So Theodosius + theological debate = Council of Constantinople 381 where Nicaea gets ratified and expanded and all these versions of ‘semi-Arianism’ get the boot from Orthodox theology.
Why did this matter so much? In some ways, Arius acted as a catalyst for the church as a broader group to wake up and say, “hey, we don’t all think the same things on this set of issues”, as well as, “gee, this is important stuff and we better figure it out.” How Jesus relates to God the Father is actually a critical question to how Christianity ‘works’. Athanasius’ writings do a great job at really attacking classic Arianism and explaining why this stuff matters – if Jesus isn’t God, is just a creature, then the doctrines about salvation have to be fundamentally altered too. Only God can save, if Jesus isn’t God, he can’t save. That’s about how it goes. If Jesus isn’t God, he also shouldn’t be worshiped as God – that’s idolatry. But if Jesus is God in the same way that God the Father is, then isn’t Arius right and there are two ultimate Principles in the universe – and this is polytheism or dualism at best?
All these things mattered because theology mattered to people, to believers in the fourth century (and later). It wasn’t abstract speculation, it mattered because God mattered to these people, and ‘getting it right’ mattered to them.
Sources: Anatolios, K. Retrieving Nicaea, 2011.
Ayres, L. Nicaea and its Legacy: an approach to fourth-century Trinitarian theology. Oxford : Oxford University Press, 2004.
Behr, John. The Nicene Faith. 2 vols, Crestwood, N.Y. : St. Vladimir's Seminary Press, 2004.
Hanson, R.P.C. The search for the Christian doctrine of God : the Arian controversy, 318-381. Edinburgh : Clark, 1988.
Williams, Rowan. Arius: Heresy and Tradition, 2002.