1. Wasn’t the Virgin Birth Story Derived From Pagan Myths?
According to this view, the accounts of Matthew and Luke arose among Greek Christians who were acquainted with the many myths in paganism that have to do with virgin births of various Greek gods and superheroes. For examples, the birth of Perseus was conceived when the god Zeus, appeared in the form of shower of gold, had sex with his mother, Danaë.
Nevertheless, a careful comparison of the biblical accounts of Jesus’ birth with the many miraculous birth stories would reveal that almost all the pagan accounts involve a sexual encounter between a god and a human woman because the god’s lust. In any of these cases, the woman had no possible claim to be a virgin, and if she was a virgin before the encounter, she certainly was not after the encounter.
This is in stark contrast from the asexual nature of Mary’s experience in the gospel account. There is no hint of God’s lust for Mary in any way parallels to that of Apollo for the mother of Octavius.
2. Wasn’t the Virgin Birth Story As A Result of Misinterpretation of Isaiah 7:14?
Perhaps the account of the virgin birth was the result of misinterpretation of the passage in Isaiah:
Therefore the Lord himself will give you a sign: The virgin will be with child and will give birth to a son, and will call him Immanuel (Isaiah 7:14, NIV)
Since this is a prophecy concerning a future virgin birth, it is claimed that church “created” the virgin birth in order for the prophecy fulfillment to take place.
However, it has to be acknowledged if we take into consideration the original context of Isaiah’s prophecy, it may not be exclusively about the virginal birth of Jesus. Rather, it referred to the birth of Hezekiah, the son and successor of King Ahaz.
This is because the Hebrew word where we get the word “virgin” in Isaiah 7:14 (NIV) is the word “`almah”. This feminine noun means a young woman, which may or may not be a virgin.
Thus, as Stein said (in Jesus The Messiah: A Survey Of The Life of Christ, IVP Academic Press, p66):
“…whereas the interpretation of Isaiah 7:14 as referring to the virgin birth is understandable in the Christian church due to an already established tradition of the virgin birth, the reverse is not at all likely….It was the story of that gave rise to the messianic interpretation of this passage (of Isaiah 7:14), not the reverse.”
In other words, it is most probable that Isaiah’s prophecy in 7:14 has dual fulfillment, initially in Isaiah’s day, and ultimately, at the birth of Jesus.
3. Wasn’t the Virgin Birth Story Derived From Jewish Thoughts?
Closely linked to the above point of contention, according to some Jewish sources, the Greek word for virgin is the word “parthenos”. Jesus, it was argued, was not born of a virgin but was the illegitimate offspring of Mary and a soldier named Panthera. Thus Jesus was not conceived supernaturally to a virgin (parthenos). This whole myth of virgin birth was to cover up Jesus’ illegitimacy resulting from Mary’s adultery with Panthera. This is clearly a parody with the switch of the ‘r’ and the ‘n’. There was no such evidence to support such theory.
 See Probe Ministries Article: Was Jesus Really Born of a Virgin? By Michael Gleghorn in Leadership University website. URL: http://www.leaderu.com/orgs/probe/docs/virgin.html