2. Britain’s time as part of the Roman Empire saw it exposed to many new religions
From the mid to late imperial period, towns in Roman Britain was exposed to many new up and coming cults that originated in the eastern Roman Empire. These mystery cults offered both worldly and otherworldly benefits to their adherents. Christianity was just one of those cults. No physical evidence- such as public churches and iconography- exists for Christianity in Britain before the fourth century. This lack of evidence is most likely because, before this time, the religion was illegal and adherents needed to be discrete. However, this aside, it seems Christianity had stiff competition from a variety of other eastern cults.
One of these was Mithraism, a Persian cult that had become particularly popular with soldiers and merchants across the empire. Numerous Mithraea, the semi-subterranean halls were the cult’s initiations took place, have been found around Roman forts and major Roman settlements such as London. Archaeologists discovered the London Mithraeum in 1954, in what would have been the heart of Roman Londinium. First constructed in the mid-third century AD, by the time Christianity had legally establishing itself in the fourth century, it was still going strong. Christianity, it seems, had plenty of competition for the hearts and souls of the Romano British.