Here's a bit more on Mithra's.
Before you read this.....have you looked at biblical apologetics on this subject yet? Do you plan to?
Mithras had had twelve followers with whom he had shared a last sacramental meal. He had sacrificed himself to redeem mankind. Descending into the underworld, he had conquered death and had risen to life again on the third day. The holy day for this sun god was, of course, Sunday (Christians continued to follow the Jewish Sabbath until the fourth century). His many titles included ‘the Truth,’ ‘the Light,’ and ‘the Good Shepherd.’ For those who worshipped him, invoking the name of Mithras healed the sick and worked miracles. Mithras could dispense mercy and grant immortality; to his devotees he offered hope. By drinking his blood and eating his flesh (by proxy, from a slain bull) they too could conquer death. On a Day of Judgement those already dead would be raised back to life.
All this may surprise modern Christians but it was very familiar to the Church Fathers [See e.g. Justin, Origen, Tertullian], who filled their ‘Apologies’ with dubious rationales as to how Mithraism had anticipated the whole nine yards of Christianity centuries before the supposed arrival of Jesus – ‘diabolic mimicry by a prescient Satan’ being the standard explanation. Pagan critics were not slow to point to the truth: Christianity had simply copied the popular motifs of a competitive faith.
Mithras was proclaimed the principal patron of the empire by Aurelian in 274 AD (on December 25th he dedicated a temple to the sun-god in the Campus Martius). Mithraism was adopted by Diocletian in 307 AD and by Julian as late as 362 AD. The cult was driven from the scene over the next hundred years by furious and sustained attacks from Christianity.