Inclusion of other deities
Roman primitive religions were modified both by the addition of new beliefs in later times, and for the assimilation of a great part of Greek mythology. Thus, Roman religion was consolidated before the start of the literary tradition, therefore, the early Roman writers who wrote about their religion were unaware of its origins in most cases, such as the polygraph of the 1st century BC Marcus Terentius Varro. Other writers, like the poet Ovid in his Fasti, with a large influence of Alexandrian models, incorporated Greek beliefs to fill gaps in the Roman tradition.
The absorption of the native gods of the neighboring countries came when Rome conquered the surrounding territory. The Romans used to give the local gods of the conquered territory the same honors as their own. On many occasions, they “invited” the newly assimilated divinities to move their residence to new sanctuaries in Rome. In addition, the growth of the city attracted foreigners, who were allowed to continue the worship of their gods. Along with Castor and Pollux, through this process of acculturation, seem to have contributed to the Roman pantheon Diana, Minerva, Hercules, Venus, and other deities of lesser rank, some of which were Roman and others came from Greece.
The first Eastern religion who came to Rome was the worship of the goddess Cybele and her lover Attis: it was a divine couple. Cybele, called “great mother” symbolized fertility and the power of nature. The symbol of the cult of Cybele was a black meteorite. It was a primitive and violent religion: in the ceremonies of the cult of Cybele, the faithful were sprinkled with the blood of the victims, they should purify the person and make him immortal.
From Iran came Mithras. He was a soldier-god. The Persians saw Mithras as an intermediary between good and evil forces. After an impressive ritual, in which the faithful was covered by the blood of a slaughtered bull, he became a Mithras soldier, as Mithras, at the beginning of the world, captured a large bull that symbolized him and sacrificed it by order of God Sun.
The important Roman gods and goddesses ended up being identified with the Greek gods and goddesses more anthropomorphic, and whose attributes and myths were also incorporated.