The Council of Nicaea (325): Lessons from the 1700th Anniversary
By Dr David Gwynn, Reader in Ancient and Late Antique History, Royal Holloway, University of London. The following is a reprint of the talk he gave at the 2025 AGM.The Council of Nicaea in 325 – for which 2025 is the 1700th anniversary – is remembered as the first ecumenical council of the Church, its decisions recognised by all branches of Christianity. Above all, the council is remembered for composing the original Nicene creed, which is still used every Sunday in many modern churches.
Actually, this is not precisely true. The original creed composed at Nicaea in 325 is on the handout at the end of this article. Those familiar with the creed used in modern churches will realise they are not quite the same. What is called the “Nicene Creed” used in modern churches is a modified version of the original Nicene creed, and is technically the Niceno-Constantinopolitan Creed of 381. I will circle back to the need to revise the original Nicene creed towards the end of this paper. But the fame of Nicaea is genuine, and the council was a crucial landmark in Christian history.
To understand why requires a short explanation. I am a historian by profession, and when drawing lessons from past events historical context matters. So, before I turn to consider some of the lessons that the Council of Nicaea offers to modern audiences, a little background is necessary.
One admission needs to be made at the start. We actually know very little about what really happened at Nicaea in 325. There are no Acts recording the debates, unlike for other major councils where we can reconstruct the order of proceedings and even some of the arguments as they unfolded. All we have are a scattered collection of letters and other documents, together with the reports of three eyewitnesses who unfortunately contradict each other. Pulling that evidence together is highly complex. Under “Further Information” below, I have noted a forthcoming book collecting the evidence which I am currently preparing together with two Emeritus Professors and a Syriac language specialist from Leuven! That book is due to appear in December 2025, and provides the research on which this paper is based.
Happily, for my current purposes, most of the academic debates surrounding the Nicene evidence do not concern us here. We do know the key issues debated at Nicaea and the key decisions reached, and a basic outline is not hard to summarise.
The council met in the year 325 in the city of Nicaea in Asia Minor – modern Iznik in Turkey, not far south-east of Istanbul. In 325, the Roman empire was still at almost its greatest extent, spanning from Britain to the Northern Sahara and east towards Mesopotamia and controlling the entire Mediterranean Sea. But Christians were still only a minority group within that empire, perhaps numbering c.10 million in an empire of c.60 million.
Moreover, the status of Christianity had fluctuated drastically in the two decades leading up to Nicaea. In 303 the last attempt by the pagan Roman emperors to crush Christianity began, the Great Persecution. All the clergy who attended the Nicene council lived through that Persecution, and some had been imprisoned or seen colleagues killed. Yet in the years immediately before Nicaea the Church’s fortunes had been dramatically transformed. In 312, Constantine became the first Roman emperor to embrace Christianity and offer imperial support to the Church. Originally Constantine only ruled the western half of the empire, but in 324 he conquered the east and united the entire empire under his control. Now all Christians within the empire could benefit from his patronage, and the Council of Nicaea in 325 thus met at a turning point in Christian history and in the presence of the Christian emperor.
The Christians who had experienced the Great Persecution understandably welcomed the rise of a Christian emperor. Imperial patronage brought increased Christian numbers, prestige and wealth, reflected in elaborate church buildings and bishops able to influence imperial policy. But imperial involvement also intensified debates that were already ongoing across the Church. Christians had always proclaimed their unity in Christ, yet there had also always been differences – in theology, organisation, and style of worship. Constantine promoted unity, but what he discovered when he conquered the Roman east in 324 was that Christians were particularly divided on two crucial issues.
One issue concerned Easter, the most important early Christian festival, and specifically when Easter should be celebrated each year in relation to the Jewish Passover, with different Christian communities following different dating practices. The other and still more complex issue concerned the theological relationship between the Father and the Son, and how to reconcile the Christian belief in one God with the divine Trinity. All Christians agreed that the Son was in some sense divine, but how could the Son’s divinity be expressed without either separating the Son as a second God or blurring the identities of Father and Son? This theological debate became known in Christian tradition as the “Arian Controversy”, as it began with a dispute in Alexandria between the presbyter Arius and his bishop Alexander and then spread across the eastern Church.
Both these issues were of fundamental importance to Christianity, and both had caused increasing conflict in the years before Constantine unified the empire. Constantine also wanted a united Church, but he recognised that these were not debates that he could resolve alone. His solution was to summon a great council, the largest gathering in Church history down to that point and the most representative Christian assembly since the apostolic council of Jerusalem.
The traditional number of bishops present at Nicaea was 318, but this was a later figure taken from the number of Abraham’s servants in Genesis and the real number was around 250. The council was not in fact truly “ecumenical” (literally worldwide, and really meaning across the Roman empire). Only a few clergy came from the west – one bishop from Spain, one from North Africa, and 2 presbyters representing the bishop of Rome. There was also a bishop from the Persian empire further east. But the vast majority were Greek-speaking bishops from the eastern Mediterranean.
The council began in late May 325 and ended in early July. Each of the major issues was debated in turn, and the council issued a series of decisions – the original Nicene creed, an Easter decree, and 20 canons on questions of discipline (one question not apparently discussed was the canon of scripture which was broadly agreed by 325 although with ongoing debates notably concerning the Catholic Epistles and Revelation). Their work complete, the council ended with an imperial banquet which one eyewitness compared to an image of the kingdom of Christ.
The Council of Nicaea was without question one of the most remarkable events in Constantine’s reign and a landmark in Church history. But – as you have probably realised – the story is not as simple as I have outlined nor was Nicaea as successful as Constantine believed. The council and its aftermath raised a series of issues that are still highly relevant to religious and political debates today, and I want to highlight a few of those themes here.
1. One core issue Nicaea raises is how to resolve disputes – who should have the authority to decide on questions which divide a religious community, particularly on questions leading to conflict and potentially open violence? This is an issue that every major religion has faced with the passing of its original leaders – Christ and the apostles, Buddha, or Muhammad. In theory, Christianity can appeal to scripture, which all recognised as authoritative. But on major questions, as at Nicaea, scripture does not provide definitive answers. The key term included in the original Nicene creed, that the Son was homoousios (consubstantial or of one essence) with the Father, came from Greek philosophy and has no scriptural basis.
One alternative when disputes are raging is simply to let people argue. This was in fact Constantine’s first reaction when he heard about the theological debates, writing to Arius and Alexander and asking why they could not agree to disagree like philosophers did. But inaction is difficult when the debates are leading to social disruption, and particularly so for a religion like Christianity which emphasises a single truth. The Council of Nicaea was a remarkable attempt to gather as many bishops together as possible and so settle the argument by a public consensus. But even then the council could never be fully representative, and those in attendance disagreed on what the decisions meant including the theology of the creed. The council was also led by bishops, with lay voices absent from our evidence, with the sole exception of emperor Constantine.
2. A second issue raised by Nicaea, which flows directly from the question of authority, is the relationship between religious debates and wider government, or in Christians terms Church and State. This is not a simple division between sacred and secular as the government often holds its own religious views, which was certainly true of the emperor at Nicaea. Constantine was a committed Christian (although only baptised shortly before his death in 337) who believed strongly that uniting Christians was a political goal and his spiritual duty.
But involving imperial power inevitably changed the nature of Christian debates. Imperial patronage made a gathering the size of Nicaea possible (the bishops travelled to the council using the imperial postal system, which Constantine placed at their disposal). And it was Constantine who legally enforced the council’s decisions and sent Arius, whose teachings were condemned at Nicaea, into exile.
Constantine wanted unity and favoured those prepared to compromise over more extreme viewpoints. Strikingly, however, the emperor did not attempt to impose his own judgements on Nicaea. He repeatedly insisted that it was the bishops who had to decide, and hailed the verdict of the council as divine judgement. The relationship between Constantine and the bishops thus worked in both directions, and set a precedent that would be followed to varying degrees in subsequent centuries. Direct conflict between Church and State was not the solution, and here Nicaea does offer a valuable model.
3. Thirdly, and perhaps most importantly in our modern climate, the debates surrounding Nicaea highlight the tension between the ideal of unity and the reality of difference, and where we might seek a middle ground.
Unity was a central theme at Nicaea. All bishops had to sign the creed, even though it was widely agreed that the divine mystery surpassed human understanding. All churches were instructed to celebrate Easter on the same day, as Constantine insisted in his letter after the council (a passage from which is quoted on the handout). And the disciplinary canons laid down the need for uniform practices, with the final canon (quoted in full on the handout) requiring all to pray standing.
For Christianity, unity was unquestionably important both spiritually and in the historical context of Nicaea. The Church’s unity as the body of Christ is a core theme from the New Testament texts onwards, just as Constantine saw unity as essential to secure divine favour. And at a time when Christians were still a minority within the Roman empire, unity was vital in holding the religion together. A repeated argument in the Nicene documents is the fear that Christian divisions will make non-Christians laugh and discourage potential converts.
But unity comes at a price. The Council of Nicaea was part of a wider process which saw Christianity increasingly tightly defined, a process which accelerated from Constantine onwards. Yet defining what was acceptable also meant hardening the lines, with less scope for innovation and greater condemnation of those who were excluded. After all, it has always been easier to define what one rejects than exactly what one believes.
Thus the original Nicene creed included anathemas against views which were no longer acceptable. Arius became remembered as one of the greatest enemies of Christianity, and attributed with a range of erroneous views many of which he never held (most famously that he denied that the Son was divine at all). His writings were ordered burnt, which is why few survive. Many of the actions against Arius were then repeated against later figures condemned as heretics, and the entire approach focuses on condemnation rather than conciliation – much like most political rhetoric today.
Finally, there is one last lesson I would like to suggest could be taken from the Council of Nicaea. Judged by the aim of achieving unity, the Council of Nicaea failed! Short term unanimity was achieved, partly by exiling anyone who refused to agree. But long term, the differences remained. Christians continued to pray in varying ways, as they still do today. Easter is still celebrated on different dates, notably between the western and Orthodox churches. And the theological debates over the relationship between Father and Son continued. 50 years after Nicaea, a Christian writer in Constantinople wrote about his experiences in the city:
“If you desire someone to change a piece of silver, he philosophizes about the Begotten and the Unbegotten. If you ask the price of a loaf of bread, you are told by way of reply that the Father is greater and the Son is subordinate. If you enquire whether the bath is ready, the answer is that the Son was made out of nothing” (Gregory of Nyssa). Those are all theological doctrines that were under debate in 325.
This is not to suggest that the Council of Nicaea did not matter. It was a remarkable gathering that happened at a crucial time for Christianity. But the council was not the beginning or end of debates. To return to the point I raised at the beginning, the reason that the Nicene Creed was reworked in 381 into the form widely used today is that it took another 50 years of debate after Nicaea to agree on what the creed should mean. And that debate was not decided by bishops in council, or by emperors passing laws. It was wider discussion across the Christian communities in both east and west which led to a gradual consensus. There could be a lesson there that some modern religious and political leaders might benefit from learning.
Further Information
David M. Gwynn, Richard Price, and Michael Whitby, with Philip Michael Forness, Documents of the Early ‘Arian’ Controversy and the Council of Nicaea (Liverpool University Press, 2025)
Young Richard Kim (ed.),The Cambridge Companion to the Council of Nicaea (Cambridge University Press, 2021)
Also by David M. Gwynn
Athanasius of Alexandria: Bishop, Theologian, Ascetic, Father (Oxford University Press, 2012)
Christianity in the Later Roman Empire: A Sourcebook (Bloomsbury, 2014)
and D. Brakke, The Festal Letters of Athanasius of Alexandria, with the Festal Index and the Historia Acephala (Liverpool University Press, 2022)
THE COUNCIL OF NICAEA (325)
The Original Nicene Creed
We believe in one God, Father, Almighty, maker of all things visible and invisible; and in one Lord Jesus Christ the Son of God, begotten from the Father as only-begotten, that is, from the essence of the Father, God from God, light from light, true God from true God, begotten not made, consubstantial (homoousios) with the Father, through whom all things came into being, both those on heaven and those on earth, who for us men and for our salvation came down, was incarnate and became man, suffered, and rose on the third day, ascended into heaven, and is coming to judge the living and the dead; and in the Holy Spirit. Those who say, ‘There was once when he was not’, and ‘Before being begotten he was not’, and that ‘He came into being out of nothing’, or assert that the Son of God is from another subsistence or essence, or is changeable or mutable, the catholic and apostolic Church anathematizes.
Canon 20 of Nicaea
While some bend the knee on Sundays and during Pentecost, the holy council, in order that all things may be observed in the same way in every diocese, decrees that prayers are to be offered to the Lord standing.
Constantine, Letter to the Churches after Nicaea
When as many as possible had gathered together (and I myself was present as if one among them, for I would not deny something about which I am especially happy, that I was your fellow-servant) every matter received a proper examination to the point where a doctrine pleasing to God who supervises all things was brought to light for agreement in unity, in such a way that no scope was left thereafter for dissent or controversy over the faith.
There was also a discussion about the most holy day of Easter, and it was resolved by common consent that everyone everywhere should celebrate on one and the same day. For what could be better for us and what more hallowed than that this feast, from which we derive our hope of immortality, should be observed by all without fail in a single rule and with a clear rationale?