One of the more common claims that Christianity was influenced by paganism involves the ancient Roman cult of Mithras. This might be partly due to the popularity of the best-selling novel, The Da Vinci Code, by fiction writer Dan Brown:
"Nothing in Christianity is original. The pre-Christian god Mithras - called the Son of God and the Light of the World - was born on December 25, died, was buried in a rock tomb, and then resurrected in three days. By the way, December 25 was also the birthday of Osiris, Adonis, and Dionysus. The newborn Krishna was presented with gold, frankincense, and myrrh." - The Da Vinci Code.
As is true with many of the claims that Christianity borrowed from paganism, there are no historical sources to support the allegations:
"Mithraic studies do not find any attribution of the titles 'Son of God' or 'Light of the World,' as Brown claims. There is also no mention of a death-resurrection motif in Mithraic mythology. ... There is not a single story in actual Hindu mythology of Krishna being presented with gold, frankincense, and myrrh at his birth." - de-coding Da Vinci: The facts behind the fiction of The Da Vinci Code, by Amy Welborn.
And as for the claims involving Dec. 25, it is important to note that the New Testament does not claim that Jesus was born on Dec. 25, and that the tradition of Christmas on that date is a matter of tradition, not a matter of theology. The pagan celebrations that took place on or near Dec. 25 during ancient times did not change Christian theology. Christian theology, however, did change the nature of the celebrations involving Dec. 25.
The ancient practitioners of the cult of Mithras did not provide us with writings about their beliefs. They did not leave behind a religious text for us to study. Much of what we presume to know about the traditions of Mithras comes from scholarly speculations about artwork found in Mithraeums that were created during the second, third and fourth centuries, after the time of Jesus Christ.
Franz Cumont, a scholar credited with the beginnings of scholarly research into the study of Mithras, paradoxically, and without explanation, claimed that the birth of Mithras was witnessed by shepherds and that Mithras was born before men and animals were created. Compare these two passages from Cumont's The Mysteries of Mithras, which was published in 1903:
"The tradition ran that the 'Generative Rock,' of which a standing image was worshipped in the temples, had given birth to Mithras, on the banks of a river, under the shade of a sacred tree, and that shepherds alone, ensconced in a neighboring mountain, had witnessed the miracle of his entrance into the world. They had seen him issue forth from the rocky mass, his head adorned with a Phrygian cap, armed with a knife, and carrying a torch that had illuminated the somber depths." - page 132 of an English translation of The Mysteries of Mithras.
"For although the shepherds were pasturing their flocks when he was born, all these things came to pass before there were men on earth." - page 133 of an English translation of The Mysteries of Mithras.
Given the incompatible accounts involving the birth of Mithras, one might conclude that the myth of his birth changed over time, adopting and adapting elements from Christianity, even though those elements conflicted with the original Mithraic myth. In any event, there is a fourth century AD bas-relief depicting the birth of Mithras that includes figures who appear to be shepherds. But this artwork is too recent to have influenced the New Testament, and not old enough to prevent someone from claiming that it was influenced by the New Testament.
Aside from any debate involving the chastity of the rock from which Mithras is hatched, there is little, if any, opportunity to seriously compare the "virgin" birth of Mithras to the birth of Jesus.
