Alice Roberts: “Christianity didn’t invent itself as an empire from nothing: it adapted existing Roman structures”
Alice Roberts speaks to Danny Bird about the evolution of the new religion that swept across the Roman empire and beyond
Danny Bird: What made you decide to write about the collapse of the western Roman empire and the rise of Christianity?
Alice Roberts: I’ve long been fascinated by this historical period, especially in Britain, where written records are scarce. This book grew from my interest in burial archaeology, shaped by excavations I took part in 20 years ago on a Welsh cliff. Bones were eroding from the cliff face, and we uncovered cist graves – stone-lined, coffin-like structures – some dating from as early as the fifth century. One grave even had a stone lid carved with a simple cross. These early Christian burials sparked my curiosity.
More recently, I visited an excavation at Llantwit Major, where archaeologists are investigating what may be Britain’s earliest monastery, possibly dating to the fifth century. This raised further questions: why was Christianity spreading so early? And who was behind it?
Rather than relying on broad generalisations, my book focuses on individuals: the people who carried Christianity across regions, and their motives. A story that began with burials in Wales led me across the Roman world from Istanbul (formerly Constantinople) to Alexandria, aiming to find out how Christianity spread so widely, and what that reveals about the fall of the western Roman empire.
Christianity presents itself as a faith for the powerless, but your book suggests that it was adopted by urban elites in its early centuries. How does this challenge the mythology surrounding its origins?
It stands in stark contrast, really. It’s a tricky point, because those writing about Christianity were necessarily literate members of the elite. So, from the outset, we’re seeing a movement that appears to have spread among relatively well-off individuals.
By the fourth century, it had clearly reached the highest echelons of Roman society. Emperor Constantine had begun to take notice, convening a council of bishops in AD 325. But even in the earliest years, this was a movement involving influential figures.
Take Saint Paul – or Saul, as he was originally known. One of his first actions was to meet the governor of Cyprus – not preaching to the poor but engaging with powerful individuals in the Roman empire who had the means to support him. The governor then sent him back to what is now Turkey to reconnect with his family. It seems that Paul recognised that patronage by adopting the governor’s name, ‘Paulus’ – which is a very Roman thing to do when offered someone’s backing.
What’s your take on Constantine? Is it right to describe him as the ‘Christian emperor’?
It’s not as straightforward as it seems. We have a biography written after his death by Eusebius, who explicitly claims that Constantine was Christian and experienced a conversion on the way to the battle of the Milvian Bridge. Eusebius describes Constantine having a vision and carrying a Chi-Rho [a combination of chi and rho, the first two letters of the Greek word for Christ] into battle, supposedly with Christ supporting him.
It’s quite striking, because at that point the context is entirely military: Christ becomes someone you want on your side as you move to defeat the emperor in Rome and claim sole rule. (Constantine was never destined to be emperor; he effectively eliminated the other three rulers until he was the last man standing.) Eusebius asserts that Constantine’s conversion occurred en route to that decisive battle. Afterwards, Constantine erected a triumphal arch in Rome. If the vision and conversion had truly occurred en route to the Milvian Bridge, you might expect some Christian symbolism on that arch – but there’s none. Instead, it’s full of traditional Roman iconography.
What’s important to remember is that none of this history comes to us without agenda. Any written account, then or now, reflects the perspective of its author. Eusebius – a bishop – clearly had reasons to portray Constantine as a committed Christian. However, when you examine Constantine’s broader communications – particularly coins, which were vital tools of imperial messaging in a largely illiterate empire – you see something different. His coins continued to depict Roman gods including Sol, to whom he appeared especially drawn, well after his supposed conversion.
That led me to investigate the Chi-Rho more closely. More than 1,000 different coin designs were minted during Constantine’s reign, and only a handful bear the Chi-Rho. Even on those coins, it appears in subtle ways: on a military standard, on a helmet – all very martial in character.
What surprised me most was discovering the Chi-Rho’s ancient origins. The symbol appears in pre-Christian literature and papyri. There’s even one on a Greek bust dating back to a time before the supposed birth date of Jesus Christ. The most plausible explanation from the papyri is that Chi-Rho was originally an abbreviation for the Greek word archōn, meaning ‘ruler’, not Christos as Eusebius claimed.
So even if Constantine did carry the symbol into battle, did it mean Christ? Or was that the first time anyone interpreted it that way? Up until then, it meant something else entirely. And we can’t even be sure he used it in the battle. Another contemporary account says he carried a cross, not a Chi-Rho.
Why do you think the early Roman church was able to so deftly fill the power vacuum as imperial rule declined?
Christianity didn’t invent itself as an empire from nothing: it adapted existing Roman structures. Early on, it functioned like a collegium – a Roman guild – offering social support, patronage and mutual aid, just as Roman professional associations did. This model suited the well-to-do among Roman society, and helped embed Christianity within everyday life.
As elites adopted Christianity, it became tightly woven into their world. Roman aristocrats were educated in the liberal arts, and expected to govern provinces and cities. Over time, church institutions began to provide this same education, adding scripture to the traditional Roman curriculum, the cursus honorum, which fast-tracked noble-born Roman men into various civic offices. Christianity thus became the default cultural and ideological framework for elite careers.
By the fifth century, bishops had effectively become city administrators, assuming roles once held by imperial officials – such as distributing the grain dole. Rather than creating something entirely new, Christianity absorbed and continued Roman civic functions.
This fusion made the church remarkably resilient. As the western Roman empire fragmented, Christian bishops continued running cities. In Gaul, for instance, elite families retained their status across the Roman, Visigothic and Frankish regimes. Individuals such as Saint Sidonius Apollinaris exemplify this continuity, remaining influential under the shifting political circumstances.
It’s unlikely that anyone at the time consciously planned to create a resilient ideological-administrative system that could survive the empire’s collapse. They were probably more concerned with preserving their own careers and ensuring opportunities for their children. For instance, elite Roman families would have been thinking pragmatically about how to secure a future for their sons amid instability.
Of course, reducing everything to economics would be simplistic. Christianity was also a compelling system of ideas and belief. Many were genuinely devout, drawn to the religion for spiritual reasons, whereas others were more focused on its social and political benefits. These different motivations coexisted and contributed to Christianity’s development. There was no single way to be a Roman Christian.
Is this Roman-ness still evident in Christian practice and ritual?
The fact that the pope still rules from Rome and has the title of Pontifex Maximus (the most senior priestly rank in the ancient Roman religion), together with the church’s use of Latin and its adoption of imperial purple, all perpetuates this legacy. Plus, high-ranking members of the church are often canonised, echoing the Roman practice of deifying emperors.
I traced some of these continuing rituals in my earlier books. When writing Buried (2022), I looked at Roman graveside feasting rituals, particularly at a burial in Caerleon, south-east Wales. A pipe from the surface was used by mourners to pour libations into the grave while holding feasts there – not just on the day of the funeral, but also nine days and 50 days afterwards, as well as on set days for honouring the dead.
When I mentioned this pipe burial to my Russian friend Natasha, who grew up in Siberia, she exclaimed: “We did that!” She described a day when families would gather with food in cemeteries, the adults drinking vodka. She believed this was a Russian Orthodox celebration called ‘Parents’ Day’. When I researched further, I discovered that it mirrored the Parentalia festival of the ancestors in the pre-Christian Roman calendar.
These traditions carried over into Christian practice. And such customs persist in both the Greek and Russian Orthodox calendars, as well as in the Catholic church and the Church of England. For instance, the moveable feast known as Pentecost occurs 50 days after Easter; elements of Pentecost recall Rosalia, an ancient Roman summer day of the dead, when graves were decorated with roses. It’s another example of Roman traditions persisting in Christian ritual to this day.
A few weeks ago, I happened to be in Orvieto, Italy, on Pentecost. A friend told me to look out for the medieval procession, so I stayed to watch. It was remarkable – people in full medieval dress parading through the streets to the cathedral, and women carrying great armfuls of flowers. The tradition continues.
What was the relationship between Christianity and pre-existing faiths and philosophical thought?
The early Christians were Jewish, and Christianity emerged within a Hellenistic-Roman context. These influences were deeply intertwined. Greek philosophy played a huge role in shaping Christian ideas but, from the start, theology was diverse and fragmented.
To maintain unity and authority, the early church had to suppress doctrinal splits. Councils such as that at Nicaea (now İznik, Turkey) in AD 325 were about enforcing consensus, not simply defining belief. Still, divisions continued: between east and west, and, much later, Protestant and Catholic, because interpretation remained contested.
Claims of Christianity’s radical uniqueness are often overstated. There are strong parallels with other cults, such as that of Mithras, and even Roman emperors’ devotion to a single god in the classical pantheon suggests a tendency towards monotheism. The term ‘paganism’ to describe non-Christian beliefs is a Christian invention, originally derogatory, which implied that the individuals who adhered to such beliefs were rustic or not ‘soldiers’ of Christ. We still use it for lack of a better alternative, though it defines by exclusion.
The idea that Christianity invented charity is false, too. Roman society valued public service, and philanthropy was expected, especially from the elite. Caring for the vulnerable was essential to civic life. What Christianity did was adapt to the needs of growing urban centres. As cities expanded and poverty increased, the church offered a system to manage – not eliminate – urban destitution. Supporting the poor served both moral and political aims, helping to extract wealth from the rich while reinforcing the church’s influence.
How important were Roman bishops and saints in entrenching the hegemony of Christianity more widely?
That was very evident in the Celtic west, where Christianity was spreading as the Roman empire disintegrated, in locations that the empire never fully reached – places such as Ireland. You see early Christianity spreading through individuals with very Roman names – including Patricius, otherwise known as Saint Patrick.
There are fascinating tales of voyaging saints, often travelling in small coracles, sometimes even with stone coffins. These journeys were just a continuation of what the elite were already doing. They were extremely well connected. In the hagiographies and accounts of these voyages, the saints are rarely heading to places where no Christian has ever been.
By the time we hear about these saints, they’re visiting other Christians, often kings. These so-called ‘missionary’ journeys often involved being welcomed at royal courts. It’s always been about nobility and the interconnectedness of powerful families. Some of these saints were bishops, some kings; some began as generals and became bishops.
Take, for example, Germanus of Auxerre. He remained rather military in outlook. At the request of the bishop of Rome, he travelled to Britain to deal with the growing divergence in Christian practice, which was causing concerns that the British might splinter away from the church in Rome. So Germanus was sent to bring them back in line, arriving with troops and even joining some battles.
It’s striking how these figures, often romanticised as humble ascetics, were anything but isolated. They didn’t retreat from the world; instead, they established themselves close to the seats of power – for example, Saint Cuthbert on Inner Farne island, overlooking Bamburgh Castle.
Do you think it’s time we stopped talking about the ‘fall of Rome’ and start seeing it more as a rebrand?
I absolutely do. You’ve hit the nail on the head. This is essentially the thesis of my book. The Roman empire, particularly in the east, continued for another thousand years until the Ottomans entered Constantinople in 1453, marking its end.
When the Ottomans took that city, the sultans declared themselves to be the Qaisar-e-Rum (‘Caesars of Rome’). In other words, they saw themselves as the inheritors of that legacy. In the west, the empire officially disintegrated in the fifth century but, as we’ve discussed, much of its culture endured and was repurposed by those who filled the power vacuum.
If we define the empire as the emperor, then that connection is severed. But if we understand the empire as the broader system – its administration, education and social hierarchy – then that continues under the Roman church.
You’re a former president of Humanists UK and one of Britain’s best-known atheists. How did that shape your approach to this foundational era of Christian history?
I hope it didn’t, because I’m trying to approach this history by meeting people on their own terms and understanding why this set of ideas was being spread. In the book, I focus mainly on the political, economic and cultural perspectives.
In some ways, that means I’m not approaching it from a position of personal investment in the ideas themselves, though I’m fascinated by them. I know a fair bit about them, having been brought up as a Christian, and being immersed in that tradition. I’m especially interested in where those traditions come from – for example, how some church festivals today trace back to pre-Christian times.
I think Christianity is a compelling and important part of our culture. As society becomes more secular, and biblical knowledge declines, we risk losing sight of Christian history. Yet there’s still, I feel, a tendency to obscure the history of early Christianity, treating it as if it simply appeared fully formed.
For me, it’s about cultural evolution: understanding where it began, who adopted it and who helped spread it. I hope I’ve explored that as objectively as possible.
Alice Roberts is an anthropologist, broadcaster and author, based at the University of Birmingham. Her newest Channel 4 series, Roman Empire by Train, will air early in 2026. She will be touring the UK with her new book, Domination, from August to November. alice-roberts.co.uk/tour
This article was first published in the September 2025 issue of BBC History Magazine