Among the Romans, Mithraism, like Christianity was centered in the “house church.” The practice was carried out among people who were intimate with one another. Individual practitioners believed that initiation into the mysteries allowed them to receive immortality through Mithra, but also as a part of a community. Mithraism, like Christianity thought that it transformed the individual spiritually while leaving them in the same social position. The transformation of the individual was interior. It took place in the heart of the individual, and manifested itself in their position in the life of the temple, or Mithraic shrine as they advanced through the stages of initiation, but that did not mean that their status, or rank, outside of the Mithraic community would change; a slave would remain a slave, a plebian would remain a plebian. The activities of the cult were closed to the general society, they were secret and mysterious, and therefore not a cause for disturbance, or upset in the social order outside of the community.
In Roman Mithraism there were seven stages of initiation; the Crow, the Griffin, the Soldier, the Lion, the Persian, the Helio-Dromus (or Sun-Runner) and finally the Father. The symbolism of the number seven should not be lost on us, as in Christianity there are seven sacraments, seven virtues, seven deadly sins etc…The Order of Initiates were grouped in two classes; those in the first four stages counted as one class, and the last three stages counted as another class. An initiate would move up the stages of initiation until he became one with the Father and thus the Father himself. At each stage of initiation, the initiate would learn a secret code that he would later (after death) be used to get him the heavenly realm appropriate to their rank. This belief in ranked heavenly planes, and passwords to allow the individual through the gate of paradise was widely believed among practitioners of Kabalaistic (coming out of the Pharisaic Sect), and among groups of Christians who had fallen into the heretical errors of Gnosticism.
A ceremony of initiation was called a Telete from the Greek word telos meaning goal or end. In the ceremony of initiation, the initiate would first kneel before the Father. The Father would then perform a “laying on of hands,” followed by a rite similar to baptism; wherein the Father would pour water over the head of the initiate from the horn of a bull. Sometimes the rite of water would be done by full immersion. In cases where the ceremony of initiation was accompanied by an actual animal sacrifice the initiate would be splattered with the blood of the sacrificial animal, or slapped in the face with a shank of meat. In other cases; the blood would be replaced by wine. This rite of blood, wine or water is referred to as the purgation, a ritual cleansing of the individual from their sins. Sometimes the ceremony of purgation would be completed by passing a torch over the head of the individual or even touching the individual with the torch in order to symbolize a baptism of both fire and water. The purgation would be followed by the consecration or coronation where a golden crown would be placed on the head of the initiate; this crown was called the “solar crown.” Iconographically the solar crown was analogous to the Christian halo, which term is derived from the Greek; meaning disk of the sun.
There is much in this symbolism that recalls Christian rituals of initiation; so much that I will not even make an argument for how intimately linked the two systems of ritual initiation are. I will simply let the record speak for itself.
In Roman Mithraism, the initiation ceremony would be followed by a feast meant to symbolize the feast shared by Mithra and Sol. Ideally, the feast would come from the sacrifice of a bull, but this feast was not required. While the sacrifice of a bull was central to Mithraic worship, as the cult spread through the empire, and as worship became confined to house churches it is thought the sacrifice of the bull was replaced with a symbolic alternative. Any animal could serve for the feat, or even a meal of bread and wine. Because the death of the “Primal Bull” was productive of all “good things” on the Earth; any of those “good things” that come from the bull were suitable to be used in the sacred meal. This meal itself, much like the Christian Eucharist, was thought to be an effective means of salvation for the worshippers of Mithra.
This description of Mithraic practices should further our understanding of how Mithraism and Christianity were sympathetic to one another. It should not surprise us to see the markers of Mithraic worship in our own Christian tradition.
Among the Romans, the first Christian emperor was Saint Constantine, Constantine the Great, who prior to his death-bed conversion to Christianity, was also a devotee of Mithras-Sol Invictus. When Constantine was made emperor, the first coins struck in his honor depicted his face with the inscription Sol Invictus. Some scholars think that Constantine thought that he was himself, an incarnation of Sol Invictus. This may seem somewhat confusing considering that we know that Constantine attributed his victory over his enemies to Jesus Christ. Constantine’s famous vision of the Christian symbol, the Chi-Ro (Px), at the battle of the Milvian bridge (312 CE), is thought to have enabled his victory when his army was at the gates of Rome. In the minds of many practitioners of Mithraism, Jesus and Mithra may have been considered to have bene the same person; that Jesus was an incarnation of Mithra. If this is true it begs the question; if Constantine thought he was Mithra-Sol Invictus, and if Jesus was also believed to be an incarnation of Mithra, did Constantine think that he was Christ?
One thing that I know is for sure, Christianity and Mithraism, as religious and spiritual philosophies, are both filled with hope. Hope for the life of the individual; hope that the individual will ultimately experience justice. Belief that God is good, and that God has given a light to humankind that will guide us in the way to paradise.
Mithraism was less accessible to the average person than Christianity. Mithraism wanted to keep to its secret ways, at a time when Christianity was opening itself to the world, and rooting out those groups, the Gnostics who had those same tendencies toward secrecy and exclusion.
The cult of Jesus would ultimately defeat the cult Mithra in the hearts and minds of the people because, in the end Jesus was no respecter of persons, badges or offices. Jesus was for every person, everywhere, at anytime. However once Christianity ascended, becoming the official religion of the empire, priests and bishops, cardinals and popes, and ecclesiastical courts became the official arbiters of the faith, with their badges and offices becoming ever more important.
 Mithraic Iconography and Ideology, by Leroy A. Campbell, pgs. 291-305