Although they famously suppressed the Druids during their invasion of Britain, the Romans were tolerant of other religions, provided that the conquered populace incorporated the Imperial Cult into their worship. The Romans sought to equate their own gods with those of the local population. People worshipped these hybrid gods, together with ancient local deities and exotic new cults.
The classical gods of the Graeco-Roman world, such as Jupiter, Juno and Minerva, and even the divine majesty of the emperor, were honoured and worshipped at temples in the cities of Britain, and at the forts of the army stationed in the province.
Adherence to this ‘official’ religion demonstrated loyalty to the emperor, and was a prerequisite for social advance. But almost everybody had a private religious life, in which local Celtic gods and mystery cults originating in distant corners of the empire could loom large.
Both the Romans and most people in pre-Roman Iron Age Britain believed that as well as supreme or general gods, there were also local gods or spirits ( genii) in every person and place. It made sense to honour and placate them.
This meant that when the Romans came to Britain, there was no clash of belief systems. Instead, local gods were merged with the incoming Roman ones – a process known as syncretism. At Bath, the goddess Minerva was identified with the local god Sul, and similarly the Roman god Mars was identified with local war gods in the Hadrian's Wall area, where he is found as Mars Cocidius and Mars Belatucadrus.
It is often impossible to be sure which of these Celtic deities existed in pre-Roman Britain and which were imports – via the Roman army – from other Celtic societies in north-west Europe, such as the goddess Coventina at Carrawburgh.
OLD AND NEW BELIEFS
The persistence of pre-Roman Iron Age beliefs is seen in the significance afforded to horned gods, wet places, heads, and ritual wells and shafts. It is also evident in the occurrence of gods in groups of three, like the matres (mothers), and the three hooded deities (the genii cucullati) so hauntingly carved in stone at Housesteads on Hadrian’s Wall.
Alongside their own gods, the Romans introduced to Britain a range of others from outside the classical pantheon. These included Mithras, an eastern god of light and rebirth, favoured by soldiers and some urban communities. His temples have been found at forts on Hadrian’s Wall, including Carrawburgh and Housesteads.
Another introduction from a far corner of the empire was Christianity.
It is not certain when Christianity was introduced to Britain, but it became increasingly popular among the elite of the province in the 4th century, after the conversion of the emperor Constantine in AD 312.
Pagan traditions remained strong, though. At Lullingstone Roman Villa, Kent, even after the decoration of a house-church with Christian wall-paintings, there is evidence that pagan rituals continued in the same building.
Despite the Christian iconography found in this and other 4th-century villas, such as the famous mosaic from Hinton St Mary (which possibly depicts Christ), this was equally an age in which rural pagan shrines, often of pre-Roman origin, were built and embellished in large numbers across southern Britain (for example at Jordan Hill and Maiden Castle, both in Dorset).
These temples were foci for the hopes and fears of rich and poor alike, and were dedicated to both Roman and native deities. Quite humble people were literate enough to be able to write on lead ‘curse tablets’, which they nailed to the walls of shrines, inciting the gods to destroy those who had wronged or stolen from them.