To maintain control over the empire, the Romans suppressed or prohibited certain religious practices. For example, in 64 AD, the Emperor Nero banned the practice of Christianity in Rome. This ban was enforced sporadically until the Edict of Milan in 313 AD, which legalized Christianity within the empire.
In addition to suppressing individual religions, the Romans also promoted the worship of the Roman gods. The Roman government constructed temples and shrines to the gods, and required citizens to participate in religious rituals. This religious syncretism helped to unite the empire, and to establish a common identity among its citizens.
By the late 4th century AD, Christianity had become the dominant religion in the Roman Empire. The Roman emperor Constantine converted to Christianity in 312 AD, and his successors gradually replaced the traditional Roman gods with Christian symbols and beliefs.