# Why did the church become persecuting in the fourth century?

In one generation, Christians in the Roman Empire went from officially persecuted to becoming imperially-backed persecutors themselves. It's important to understand why, to prevent the church from persecuting today.

Published on: 11 Dec 2025 

In the year 325, Constantine stood before an assembly of Christian bishops. He had just the year before killed his last remaining rival in battle, leaving him as the sole Augustus of the Roman Empire, from Brittania to Arabia. The bishops must have assembled before him in reverent awe.

Many of them sported scars from torture they had endured in the reign of Diocletian, Constantine's predecessor. Diocletian had sponsored an enormous and brutal persecution of Christians. But that generation of bishops was witnessing an epochal shift of power. Over his reign, Constantine would divert large chunks of the wealth and influence of the Roman state into the safe-keeping of the bishops. Under Constantine's leadership, the bishops would be transformed from enemies of the state to the state's agents.

Official Roman persecution of Christians was decisively coming to an end. But the tragedy of the fourth century is that rather than ushering in a new age of religious tolerance, the bishops only continued the Roman habit of religious persecution, directing the force of the Empire first against internal rivals, 'heretics', and then against pagans and Jews.

Why did Constantine bestow so much power on the bishops? Part of the answer may be the creaking disfunction of the Roman state. The imperial systems for protecting the poor were falling apart. The justice system was notoriously corrupt, and was known to effectively be a means for the rich to get their way by paying for the best lawyers and greasing the palms of the judges. The poor-relief system, based on the magnanimity of local patrons, was stuttering as an increasing proportion of the aristocracy's surplus wealth went to fund the tottering military system, frequently consuming huge resources in ill-fated expeditions against the Sassanids or fighting coups and civil wars between rival emperors.

The bishops were already in control of an impressive poor-relief system within Christian communities, and, unlike the Roman system, which rewarded rich philanthropists with honours, the Christian system encouraged patrons to give anonymously via their bishop, meaning the bishops were in control of how large amounts of Christian money was spent. When Constantine ascended, they were ready to go with their own bureaucratic systems independent of the imperial civil service.

Constantine may have regarded the bishops, fresh out of persecution, as less corrupt than imperial pen-pushers. However, in the long run, the effect of his transfer of power was to transform the episcopate into an alternative civil service, perhaps no less corrupt than the first. But how did this power turn into persecution?

As the bishops became ever more powerful, Constantine and his successors became increasingly dependent on their power. Bishops had huge moral influence over their congregations, and their word had the power to stop -- or start -- riots. Emperors also needed them to keep distributing poor relief, an important foundation for the emperor's moral authority. When the hugely unpopular George of Cappadocia was installed in Alexandria in 357, the local widows refused to receive alms from him: as a result, they were physically beaten by George's imperial goons.

Since the emperors needed the bishops' support, they became increasingly willing to acquiesce to their demands. And one of the bishops' demands was that the emperor use his authority to help them crush heresy.

The bishops of the fourth century inherited a dichotomy between orthodoxy and heresy which had developed in the early church. Orthodoxy meant true belief, defined and enforced by the bishop. Whoever promoted false beliefs, and together with it insurrection against the bishop's authority, was defined as a heretic.

Orthodoxy was conceived of as the unchanging teaching of the apostles, who were in turn taught directly by the Holy Spirit. Orthodoxy might have to be re-stated as sneaky heretics sought to twist its language, but orthodoxy was never supposed to be innovative: only heresy was innovative. Further, heresy was always thought of as a combination teaching falsehoods, behaving immorally, and refusing to take part in mainstream Christian community. It all came as a package. Truth means right behaviour means loyalty.

It's difficult to explain exactly why this system emerged. It's true that faith lies at the root of Christian religion, and that Christ taught that he is truth. The Epistles are clear that false teachings can be dangerous, and Christians have a duty to resist them. But that doesn't in itself explain why the bishop gets to decide which teachings are true or false, nor why the myth of an unchanging apostolic orthodox teaching should have prevailed over the idea that Christian teaching can grow over time as it encounters new problems and contexts.

This system may have been motivated by the need for a distinguishing feature to ground Christian family identity in the absence of an identity based on nationality, social class, sex, or religion. It may also have been some kind of reaction or defence mechanism against persecution. In a world that was often hunting for an excuse to persecute Christians, it was a matter of life and death that Christian communities were tight-knit, loyal to one another, and visibly living according to the highest moral standards.

Whatever the case may be, the result by the Constantinian turning point was that bishops had significant influence over their local Christian communities, and an ideological commitment to maintaining their communities' loyalty to the bishop and his teachings.

And the bishops' desire to crush heretics only increased as the fourth century wore on. With the wealth and power of the civil service increasingly transferred to the episcopate, the aristocracy which had dominated the civil service inevitably moved in to capture the episcopate. Those aristocrats guarded their power jealously, and elections became increasingly marred by accusations of corruption. When Athanasius was elected in 328, he was accused of being underage, of bribing electors and of beating up his Meletian opponents once he got in office. No doubt, the aristocratic bishops were more than happy to use the church's concept of orthodoxy to keep out challengers, as Athanasius did when he used the label 'Arian' to describe just about anyone who wanted him out of power, no matter how distant their ideas were from those of Arius. As bishops found the need to fight ever stiffer competition for their jobs, accusations of heresy multiplied.

As a result of their dependence on episcopal power, Constantine and his successors supported the bishops in their attempts to crush heresy. The bishops appealed to the emperor to adjudicate on disputes, and the emperor responded by calling councils such as Nicaea (325), Antioch (341), Constantinople (360) and Constantinople again (381). Under the emperor's authority, bishops were exiled from their sees, and some theological views were condemned as heresy while others affirmed as orthodoxy, to justify the empowerment of some and the dethronement of others. The particular orthodoxies implied by succeeding emperors was not consistent, leading to some emperors and councils being known to history as 'Nicene' and others as 'Arian'.

Apart from simply doing a favour for the bishops, the emperors had their own reasons for wanting to defend the bishops from challengers. The bishops now had the keys to the welfare system and the justice system. The emperor therefore could not tolerate rival bishops fighting for authority. That would only undermine those systems, which underpinned imperial power and moral authority.

The emperors may also have been motivated by the need to uphold true religion and keep peace in the Empire. It was a universal consensus that, if the Empire was to flourish, it would only be with God's blessing, and that would only happen in turn if the people were united in acceptable worship. Before the Edict of Milan in 313, which finally ended official persecution of Christians in the Roman Empire, there had been a long debate about whether Christian worship counted. It was controversial because Christian worship didn't look much like worship at all to pagan eyes, in particular because Christians didn't make sacrifices. When Constantine settled the issue in favour of Christians, it must have signalled a step change, where acceptable worship became less about proper rites and more about proper belief. This trend may have led emperors to regard heresy as a threat to the Empire's security. Further, where there were schisms, there was no peace, and the Emperor's mission, to unite the world under one government in perpetual peace, was incomplete.

These forces amplified one another in a terrible feedback loop. As bishops increasingly were empowered to define and enforce orthodoxy, they increasingly monopolised local church leadership, which made them more desirable as imperial bureaucrats, which meant they got more power, which meant they were more able still to define and enforce orthodoxy. It was a spiral which led to the definition of orthodoxy being continually sharpened (even as the myth persisted, ever less plausibly, that they were defending pristine, unaltered apostolic teachings). Eventually, it pushed bishops to support persecution not only of Christians who disagreed with them, but also pagans and Jews.

Orthodoxy may also have become more important in the fourth century because of the large number of new converts. With so much influx, insiders may have felt that their core belief-identity was being threatened, and so will have enforced orthodoxy more strictly, while outsiders may have felt the need to prove their authenticity by strongly committing to orthodoxy. Committing violence against heretics, pagans, and Jews may also have functioned as a way to prove that you're an authentic Christian. This drive towards violence was pushed especially strongly from the monastic sector, which exploded in scale in the fourth century.

When orthodoxy gets sharp enough, it eventually gets sharp enough to cut the church in half. To put it another way, bishops competed to get imperial backing for their thinking, and therefore their right to power. Since this imperial backing must have some consistency to remain legitimate, this means orthodoxy gets standardised across the Empire, and that means that local differences of opinion become international schisms. Although the Arian controversy never resulted in a schism within the Empire, there were numerous schisms in the fourth and fifth centuries, culminating in the epic Nestorian schism, which split the imperial church three ways along Chalcedonian, Antiochene and Alexandrian fault lines.

My main reaction to this period of church history is dismay. It seems to me that the church was captured by the Empire and the aristocracy. The church became in large part a way for powerful people to grab, hold onto and accumulate power. When that happens today, the Gospel is suppressed, and the church loses moral authority.

To avoid this happening again, we ought to protect the right of Christians and others to believe and gather free from persecution. True belief is important, but that doesn't mean we should attempt to compel agreement. Christian leaders cannot enforce their teachings if dissatisfied Christians can just go to the church next door.

Opening communion also disempowers those forces which seek to enforce orthodoxy. If the bishop can't bar you from taking communion, they can't force you to accept what they teach or to support their political programme.

Finally, established churches are vulnerable to the perverse incentive structures of the state, and must be disestablished. The Church of England should not have seats in the Lords and should not crown British monarchs.

I believe in one holy, catholic and apostolic church -- but I do not believe in one opinion or one authority. My realistic ideal of church unity now involves a plurality of disestablished denominations which robustly disagree with one another on important points of belief, but which admit one another to communion and are willing to work together for the sake of the Gospel.

I have to caveat my pessimism about the fourth century. As much as I regret the imperialisation of the church, I remain attached to the particular orthodoxies which it produced at Nicaea, Constantinople and Chalcedon. I've been convinced that they are important ground truths for theology, and have stood the test of time because they are intellectually robust. Other creeds and councils (including creeds from fourth-century councils) have been forgotten, but these stand tall. I suppose that Nicaea, Constantinople and Chalcedon give good guardrails for theology, and, whatever the political forces which gave rise to them, have been subsequently vindicated by their theological fruits and by the enduring testimony of the church.

In summary, the church became increasingly persecuting in the fourth century as a result of the entangled interests of, on the one hand, an increasingly landed, aristocratic episcopate which needed to protect its influence amidst stiff competition, and, on the other hand, of embattled emperors who regarded the bishops as a better way of exerting the Empire's power and achieving the Empire's mission amidst the failure of the old imperial systems: provided they could be kept happy and kept in unchallenged power. This persecuting force produced the church's foundational ecumenical creeds, but was just as effective at producing disharmony as enforcing harmony, and ultimately led to the massive and ongoing Nestorian schism. This is a sober lesson for today's church, and should move us to protect freedom of belief and gathering for all, to disestablish the church and to open the communion.

