The Mithra mystery religion probably gave us December 25 as “Christ-mas”, the christian fusion of Yeshuah’s “birthday” with the older winter solstice practices of pre-christian religions.
This was a pretty good simple overview of Mithra worship, concentrating on the many Mithraem, Mithra temples, usually underground, that have been found, including many recent finds.
In later years, Christian commentators recognized similarities between Mithraic and Christian rites and were quick to condemn them. In Chapter 70 of Dialogue with Trypho, the 2nd-century Christian author Justin Martyr writes that Mithras’s worship in a cave and his “rock birth”–a frequent depiction of the god, emerging from a stone–is taken from Daniel 2:34 and Isaiah 33. The Mithraists “have no understanding” of these Scriptures, says Justin.
Justin Martyr LXXI: “And when those who record the mysteries of Mithras say that he was begotten of a rock, and call the place where those who believe in him are initiated a cave, do I not perceive here that the utterance of Daniel, that a stone without hands was cut out of a great mountain, has been imitated by them, and that they have attempted likewise to imitate the whole of Isaiah’s words?”
Daniel 2:34: “While you were watching, a rock was cut out, but not by human hands. It struck the statue on its feet of iron and clay and smashed them.”
In Chapter 66 of First Apology, Justin claims that “wicked devils…imitated” the Eucharist by creating a Mithraic communal meal. In Chapter 40 of The Prescription Against Heretics, the 2nd-century Christian writer Tertullian notes that Mithraists “celebrate also the oblation of bread and introduce an image of a resurrection.” Aside from Tertullian, however, no other ancient source scholar mentions the image of resurrection in Mithraic ritual.
Jesus was not the only deity with whom Mithras shared similarities. In the later Roman Empire, Mithras blended in with another sun god, Sol Invictus, the “unconquered sun.” Both gods appeared in the Spanish provinces around the same time, according to Jaime Alvar, an ancient history professor at the Universidad Carlos III de Madrid. Some 1st-century votive offerings in Rome even conflate the two gods into one deity, “Sol Invictus Mithras.”
By the 5th century, Mithraism faded. However, Mithras and Sol Invictus have echoes in the worship of Jesus Christ. Martin believes the ideas of brotherhood in Mithraism and apostleship in Christianity descend from collegia, or Greek social and political clubs. “My own take is that you’ve got two religions developing at the same time and in the same place and in the same culture and they’re going to develop similar kinds of expressions, symbolic expressions,” he adds.