The Religio Romana is the pre-Christian religion of Rome. Sometimes referred to otherwise as "Roman Paganism." Tacitus followed the Roman Pagan Religion. The historical basis of this religion's spirituality comes from the Pagan religions of the ancient Roman Republic and Empire. The heart of its history continues from the founding of Rome in 753 BC, to the removal of the Altar of Victory from the Roman Senate in 394 AD. In the ancient world Roman religion was practiced alongside Celtic, German, Greek, Egyptian, Persian, and Oriental faiths. This combination of different forms of belief or practice remains basic to the Roman Pagan spiritual world view.

While it is difficult to identify exactly what early Romans believed about gods and how they worshipped, there is much we know. Most of the time superstition was the motivation for much religious activity - for example, understanding the gods. Believers had a fear of upsetting the gods, who could not be trusted. In general, Roman religious practices were not associated with dogma or morals, but were based on a more or less contractual agreement with the gods.

The key religious ethic for the Romans was pietas, which refers to a sense of duty, honor, and respect for the gods. The moral beliefs of the person did not matter, so far as they performed the ritual according to the beliefs and rules of the religion. Along with the religious rituals, the Romans also offered their prayers. Do ut des was the most common form of prayer, meaning "I give so that you may give." The whole idea was to bargain with the gods and contribute to their power by adding to it with sacrifices. The gods are more powerful than humans and their power can be increased when humans offer them gifts.