Superstition was common in the private life of the Romans, as well as personal religious devotions and the traditional domestic and family cults (the pious memory of ancestors).

Sensibly, Rome respected the cults and beliefs of the peoples of the territories it conquered. Romanization, amongst other things, brought about the assimilation and syncretism of different forms of worship and the incorporation of numerous foreign divinities into the original pantheon of the Republic, particularly those from Greece and the eastern Mediterranean.

The reign of Augustus brought about major changes in the religious slant of the new Imperial structure. Official religious demonstrations quickly turned into the worship of an ideal and abstract dea Roma and of the person of the Emperor (initially deified after death, but eventually becoming a virtual living god, and even including other members of the Imperial family).

The Imperial cult, despite deviations and excesses, would have a great influence on the various areas of religion. The traditional Roman gods such as Juno, Minerva, Sylvanus or Venus had the title "august" added to their names. Refusing to render homage to the Emperor, the personification of the State, was considered a political-religious crime. Continued resistance could lead to the death penalty and was the cause of a great deal of persecution of Christian subversives.

Christianity arrived in Tarraco early, although we have no real evidence showing its firm establishment in the city until the 3rd century. In the year 259 Bishop Fructuosus of Tarraco and his deacons Augurius and Eulogius were martyred in the arena of the Amphitheatre. Many beliefs and religions coexisted, with more or less hostility, until the general imposition of Christianity, which eventually became the official religion of the Empire. These included paganism and oriental salvation religions (including the cults of Mithras, Cybele or Isis, Judaism and the Christian doctrine). Anti-pagan repressions and sectarian conflicts between Catholics and Arians were frequent right until the time of the Muslim invasion.