Was the Roman version of Jesus Christ just a retelling of Mithra mysteries?

The problem with relating later stories back to Mithra was that Mithraism was a mystery cult so we don't know all that much about it before the time of Christ. We do know that it existed before Christ and that sometime after the time of Christ these beliefs came out into the open and resembled Christianity, however we have no way of knowing whether these beliefs are the same ones being that were being practiced by the followers of Mithra in the centuries previous. In fact the more research that is being done on Mithraism the more it is starting to look like they changed there beliefs in order to mimic the incredible successful spread of Christianity, for example in later incarnations Mithras is said to be born from a immaculately from a virgin, however archaeological digs from the first century digs from the first century B.C. portray Mithras being born out of a thunderbolt striking a rock which produced him as a youth with a sword in his hands. Similar things were done by interpreting the primordial bull that Mithras was said to have slain as himself, thereby tying themselves to the Christian notion of self sacrifice after the fact. In the archaeological evidence it is clear that Mithras himself did not sacrifice himself but rather (like any good soldier god) went off, killed the monster and bathed in its blood to achieve immortality, hardly congruous to Christianity. The historical information also makes it unlikely that Christianity would have borrowed highly from Mithraism, Christianity was started by a group of poor, illiterate Jewish peasants, how under the Roman Empire would not have seen military service. Mithraism, was a mystery cult, one whose mysteries would have been kept under lock and key by its faithful, the highest ranks of the Roman Army, in Rome. It is extremely unlikely that these mysteries would have been known to the early Christians. Fascinating topic though, I'd love to hear what other people think.