The Second Book of Enoch (also called “Slavonic Enoch”) is apparently a Jewish sectarian work of the 1st century CE. The last section of the work, the Exaltation of Melchizedek, tells how Melchizedek was born of a virgin, Sofonim (or Sopanima), the wife of Nir, a brother of Noah. The child came out from his mother after she had died and sat on the bed beside her corpse, already physically developed, clothed, speaking and blessing the Lord, and marked with the badge of priesthood. Forty days later, Melchizedek was taken by the archangel Gabriel (Michael in some manuscripts) to the Garden of Eden and was thus preserved from the Deluge without having to be in Noah’s Ark.
The crucial arguments for the early dating of the text have very largely been linked to the themes of the Temple in Jerusalem and its ongoing practices and customs. Scholarly efforts have been in this respect mostly directed toward finding hints that the Sanctuary was still standing when the original text was composed. Scholars noted that the text gives no indication that the destruction of the Temple had already occurred at the time of the book’s composition. Critical readers of the pseudepigraphic would have some difficulties finding any explicit expression of feelings of sadness or mourning about the loss of the sanctuary.
Affirmations of the value of animal sacrifice and Enoch’s halakhic instructions found in 2 Enoch 59 also appear to be fashioned not in the “preservationist,” mishnaic-like mode but rather as if they reflected sacrificial practices that still existed when the author was writing his book. The author tries legitimize the central place of worship, which through the reference to the place Ahuzan, which is a cryptic name for a Jewish Temple.
Scholars have also previously noted in the text some indications of the ongoing practice of pilgrimage to the central place of worship. These indications could be expected in a text written in the Alexandrian Diaspora. Thus in his instructions to the children, Enoch repeatedly encourages them to bring the gifts before the face of God for the remission of sins, a practice which appears to recall well-known sacrificial customs widespread in the Second Temple period. Further, the Slavonic apocalypse also contains a direct command to visit the Temple three times a day, an inconsistency if the sanctuary had been already destroyed.
So it seems as though the three themes (son of Joseph, being raised after three days, virgin birth) that were originally thought to be Christian inventions seem to have precursors in heterodox Jewish literature before the Christian era.
Justin Martyr, of course, evidences that virgin births were common in pagan religions:
First Apology Ch. 21
And when we say also that the Word, who is the first-birth of God, was produced without sexual union, and that He, Jesus Christ, our Teacher, was crucified and died, and rose again, and ascended into heaven, we propound nothing different from what you believe regarding those whom you esteem sons of Jupiter.
First Apology Ch. 22
And if we assert that the Word of God was born of God in a peculiar manner, different from ordinary generation, let this, as said above, be no extraordinary thing to you, who say that Mercury is the angelic word of God. But if any one objects that He was crucified, in this also He is on a par with those reputed sons of Jupiter of yours, who suffered as we have now enumerated.
And if we even affirm that He was born of a virgin, accept this in common with what you accept of Perseus. And in that we say that He made whole the lame, the paralytic, and those born blind, we seem to say what is very similar to the deeds said to have been done by Aesculapius.
Dialogue with Trypho Ch. 67
And Trypho answered, “The Scripture has not, ‘Behold, the virgin shall conceive, and bear a son,’ but, ‘Behold, the young woman shall conceive, and bear a son,’ and so on, as you quoted.
But the whole prophecy refers to Hezekiah, and it is proved that it was fulfilled in him, according to the terms of this prophecy.
Moreover, in the fables of those who are called Greeks, it is written that Perseus was begotten of Danae, who was a virgin; he who was called among them Zeus having descended on her in the form of a golden shower.
What’s interesting is that neither Mark nor Paul mention anything about a virgin birth. Meaning that the virin birth of Jesus wasn’t any fundamental Christian dogma prior to the writing of Matthew and Luke. Ignatius writes about Jesus’ miraculous birth, but according to tradition he was writing around 96 CE, almost in the 2nd century… and his letters have been heavily interpolated. Cerinthus, a contemporary of Ignatius, said that Jesus was born from normal means by Mary and Joseph. It seems that Justin Martyr is the first unambiguous Christian witness to the virgin birth dogma.