Mithraism or the Cult of Mithras was a secretive male-only mystery religion in Rome in 2nd & 3rd centuries CE loosely based on Persian Zoroastrian beliefs, but probably did not strongly resemble the original. The primary God Mithras may have been a Greco-Roman rebirth of the Indo-Iranian God, Mithra, though the connection, besides the similarity of the name and the representation of Mithras as a Persian in imagery and writing, is not clear.
The Cult of Mithra appeared in Rome in the early 2nd century CE and was popular among men of all social classes throughout the Roman empire. Mithraism was repressed along with all the rest of the Pagan cults after Constantine’s conversion in the 4th century CE and had virtually disappeared by the 5th century. Members of the cult met in caves or cave-like temples arranged like a formal dining room, with an image of Mithras killing a bull arranged near the head of the table and astrological symbols throughout. Ceremonial activities seem to have included communal meals, initiatory ritual and seven levels of initiation. We have a limited understanding of the cult due to its secretive nature and the lack of written records.