The cult of Mithras was introduced to Rome during the 2nd century and it flourished. Originally a Persian deity, Mithras was supposed to be born of a virgin, the birth being witnessed by a few shepherds. Zoroaster's main God, Ahira Mazda made him a deity of truth and light, a sun-god equal to the Supreme Being. Mithras was strongly against Achriman, the spirit of evil. The life of Mithras ended with the slaying of a great bull, the bull representing the forces of evil. By slaying the bull and letting its blood, Mithras fructified the earth. On the Day of Judgment, the believers would inherit the world of peace and the others would be perished.
Sunday was a sacred day, their Lord’s day. On December 25th (the birthday of Mithras) there were elaborate celebrations: bells were rung, hymns sang, candles lit, and sacraments of blood and water administered to the faithful. Between December 25th and the Spring Equinox (March 21) was the 40 days of the search for Osiris which later became the Christian Lent. On the black Friday Turboilsim or bull fighting was represented with blood drinking.
Mithras, killed in the battle, was symbolically laid in a bier as a corpse. He was mourned in liturgy and was placed in a scared rock called Petra and removed many days later in a great festival. This later became the Christian Easter. Christianity like any other religion simply adopted the Pagan doctrines, rituals and festivals, so that the new religion could be spread easily to the believers of other cults of the time.
Christianity, was established by St. Paul, a genius. Jesus was born a Jew lived a Jew and died a Jew. St. Paul, gave a new meaning to his birth and death which Jesus never even thought of. The genius said Jesus, a fearless social reformer crucified by the Romans as per authorities' orders and law, did so for the sins of Humanity! How can a punishment meted out by the then authorities become an atonement for the sins of man? Hundreds were crucified by the Romans, in a similar manner, for various reasons. The new sect adopted the festivals prevailing in the Roman Empire for its easy spread.