From secret cults to Christianity, how did ancient Roman religion change so dramatically?
Ancient Rome didn’t abandon its gods overnight. The rise of Christianity was a slow transformation of the cult-based religious order that had structured Roman life for centuries
The word ‘cult’ is a loaded one in modern language. It might make you think of hooded figures huddled in dark rooms, perhaps organised around a singularly charismatic leader who exercises immense control over members’ lives.
But in the ancient Roman empire, cults were an ordinary cornerstone of society and a pillar of religious life.
This difference between modern and ancient Roman notions of cults is central to understanding one of the most significant social transformations in western history: how the Roman world moved from a polytheistic system of many gods, to a Christian empire centred on a single deity – the Abrahamic God.
As professor Philip Freeman explains, “the word cult tends to have a negative connotation, but it’s actually a good word, and we use it all the time in academic contexts.”
So what exactly were these cults, and what impact did they have on the death of the old Roman gods, and the adoption of Christianity?
Roman religion as social infrastructure
The Romans were far less concerned with what individuals believed internally than with whether they performed the correct rituals in the proper way. There was no sacred book that defined orthodoxy, and no central institution equivalent to a church.
Instead, religion functioned through a web of practices embedded in everyday life and anchored around cults.
Cults were places where people met regularly, shared meals and honoured a god together. “Think of a cult as a social group,” says Freeman, who was speaking on the HistoryExtra podcast.
One of the clearest examples of a cult still exists beneath modern London. “If you go to the financial district, you can visit the Temple of Mithras in the basement of a bank,” Freeman says.
This temple, dedicated to the god Mithras, was discovered in the 1950s. Mithraism was one of the most widespread cults in the Roman world, especially among soldiers and officials.
“That was a cult found all over the Roman empire. It was dedicated to a god, it was male-only, and it functioned as a social club as well as a religious one. There were sacrifices and ritual practices, but it was also a way to make friends and to establish business relationships.”
Pluralism as the Roman norm
An aspect of Roman religion that’s crucial to understanding how Christianity took hold is that the Romans didn’t see gods and religions as mutually exclusive. A single individual might honour household gods at home, take part in public sacrifices to civic deities, belong to a professional cult, and also be initiated into a mystery cult such as those of Mithras or Isis. None of this was contradictory.
“There was enormous variety,” Freeman says. “Some cults were absolutely secret, you could never know what went on inside them. Others were much more open.”
This pluralism made Roman religion extraordinarily resilient. New gods could be added without threatening old ones, while local traditions could coexist with empire-wide cults. As Rome expanded, it absorbed foreign deities rather than repressing them, often identifying them with Roman gods through a process historians call interpretatio romana. This was a way of integrating new communities into Roman life.
Christianity emerged “in a Roman province called Palestine at the very start of the first century AD,” Freeman explains. It developed initially within Jewish communities, sharing many of their scriptures and traditions, before gradually attracting non-Jewish converts. At first, it was a small, local cult among many.
What made it different was its exclusivity. Christians rejected the system of many gods, rather than adding their god to the system. They refused to worship other deities, rejected the practice of sacrifice, and refused to honour the emperor as a divine figure.
This alarmed the Roman authorities. Religion was a public expression of loyalty and social participation. Performing sacrifices was seen as a civic duty that helped maintain harmony between gods and state. Refusing to take part at first seemed anti-Roman, and subversive.
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This helps explain why Christianity faced periodic persecution from the outset. “It takes more than 300 years before Christianity is accepted officially under Emperor Constantine,” Freeman says.
Even then, acceptance didn’t mean dominance.
How Christianity learned to behave like a Roman cult
One reason Christianity survived long enough to gain imperial support was that it gradually came to resemble the cults that Romans were already familiar with and understood.
Like the cults, Christian communities were close-knit networks with shared rituals and mutual aid. But unlike many cults, they were inclusive, and open to men and women alike. They cared for the sick and poor, creating threads of loyalty that went beyond religious norms.
These social benefits were particularly attractive in times of epidemic, famine and economic instability – all intermittent challenges faced by the Roman empire as it progressed past the turn of the millennium.
At the same time, Christianity adapted culturally. Freeman stresses that early Christians were pragmatic.
“Christians recognised that they were not going to defeat polytheism quickly. The process had to be gradual.
“If a particular goddess was popular and people enjoyed worshipping her, Christians might say, ‘This is very much like the Virgin Mary.’”
This strategy allowed for a feeling of continuity in daily religious life, even as the theological meanings shifted.
The long fading of the old Roman gods
Even after Christianity gained imperial backing in the fourth century AD, traditional religions didn’t vanish. Imperial laws against pagan worship were unevenly enforced, especially outside major cities.
Freeman points out that “we have records from after the fall of the Roman empire showing that people in Italy, even in Rome itself, were still worshipping other gods and goddesses.” Christian writers repeatedly complained about stubborn pagan practices.
So when did the Roman gods truly disappear?
“If forced to give a date, I would probably say by the sixth century AD the old pagan religion was gone.” By then, major temples had closed and state support for non-Christian worship had ended. Christianity hadn’t destroyed the cult system, so much as it had adapted to it.
Professor Philip Freeman was speaking to Emily Briffett on the HistoryExtra podcast. Listen to the full conversation.
Authors
James Osborne is a digital content producer at HistoryExtra