Of course, most people who do not subscribe to the faith are sure to cry “foul” on this claim. And who wouldn’t? On the surface, there are a number of more likely explanations. Maybe she (the figure Mary) had premarital intercourse with her soon-to-be-husband (Joseph). Or perhaps she had had relations with another individual in Nazareth. The issue with this is, should she not be able to prove she is a virgin on the evening of her wedding night, through myths surrounding the hymen breaking upon losing her virginity, Deuteronomy 22:20-21 suggests bringing her to her father’s doorstep and having her stoned to death.
If we are to suppose that Mary actually did conceive without any intercourse (even ignoring the possibility of the god of Israel pulling a Zeus and impregnating her, as many Christians would argue against), there are problems that arise. Parthenogenesis, the concept of animals reproducing in an asexual manner, meaning conception without intercourse, would produce a child of the same gender. Birds, sharks, crustaceans, amphibians and many other types of animals are capable of this.
There has been no recorded instance of it in mammals, but, assuming 2000 years ago there was this one exception, the problem would occur that the child would have been born with two X chromosomes. In other words, Jesus would have been a woman.
Other problems arise with this account. First, there are only two instances in the New Testament of claiming that Jesus came from a virgin birth. These are in Matthew and Luke. Paul writes in Galatians 4:4 that Jesus is “born of a woman”. But this does not suggest a virgin. The Gospel of Mark, the earliest written account in the New Testament, aside from Paul’s letters, has no concept of the virgin birth. This likely suggests it was a later tradition added in, and justified, by the authors of Luke and Matthew.
It was still a belief strongly believed and used to justify the deification of Jesus, as Ignatius writes about it in Smyrneans I. It was also likely used to justify celibacy in the early church, as Paul (1 Corinthians 7) and others (Matthew 19:9-12) advocated for in the writings of the New Testament.
Other things to consider is that the authors were writing, and it appears also read, in Greek. This is important because they likely had a copy of the Septuagint or the Greek Old Testament. The word used for “virgin” in Greek is parthenos. Based upon the fact that Matthew explicitly has the angel that appears to Joseph tell him “You shall name him Emmanuel”, it is evident the author took this passage from Isaiah 7:14,
Therefore the Lord himself will give you a sign. Look, the virgin is with child and shall bear a son, and shall name him Emmanuel.
Here’s the issue. The translation that is included is how it would translate from the Greek in the Septuagint. If we correct it to how the Hebrew reads, there is a slight change:
Therefore the Lord himself will give you a sign. Look, the young woman is with child and shall bear a son, and shall name him Immanuel.
The spelling of the name aside (it’s the same name, just altered slightly from the language), the issue is that the original Hebrew used where the word “virgin”, or parthenos is, the word used is ‘almah. This word means “young woman” with no designation of virginity. The Isaiah passage also refers to a specific woman. Namely, either the wife of Isaiah or of King Ahaz, the two who are having the discussion which, it should be noted, was about protecting Jerusalem from the coming siege from the Assyrians in the eighth century BCE.So, why was it important to designate Mary as a virgin? Aside from the mistranslation from Hebrew to Greek, other ancient figures (both mythical and historical) had similar mythologies around their conception. Heracles, for example, was conceived between a mortal woman and Zeus (Diodorus Sculls, 4.9, 1-10).
Other early sources suggest that figures like Romulus, the founder of Rome, was conceived by the deity Mars (Ovid, Metamorphoses, 14:805-28). The philosopher Plato is alleged to have been conceived through his mother Amphictione from Apollo (Origen [quoting Celsus], Against Celsus, 6:8). Celsus actually says, according to Origen, that Plato’s father, Ariston, “was prevented from having sexual intercourse with Amphictione until she had brought forth the child which she had by Apollo.”
Alexander the Great is also suggested to have been born through divine conception. His mother, Olympias, is alleged to have been impregnated by Zeus (Plutarch Life of Alexander, 3:1, 3). The ultimate point to conclude is that, when we consider important mythical, theological, or historical figures, the idea of conception through divine means is what becomes a cornerstone in their story for emphasizing their importance. 
In the beginning of the Christian church, virginity was emphasized as a means for being prepared for the coming kingdom of God on earth (see any of the [authentic] writings of Paul for emphasis). When the trend of Christianity caught on in the public realm, so did the idea of virginity. Clement of Alexandria championed Paul’s views. Methods of Olympus wrote Symposium of the Ten Virgins to counter Plato’s Symposium and it included speeches from ten virgins that advocated for chastity, as procreation was now obsolete with the coming of Gods kingdom. The Catholic church even attempted to make the world chaste in the tenth century. When that failed, it made the clergy abstain in 1215.
All this because they thought a Jewish apocalyptic preacher was believed to have come from a virgin. And allegedly being a virgin meant acceptance into the elitist club called Heaven.
For more on virginity, sex, and other issues of intimacy that stem from the Christian Bible, check out my latest book What the Bible Rally Does (and Doesn’t) Say About Sex: the How, When, Why, and with Whom of Scriptural Prohibitions and Permissions. Available now from Pitchstone Publishers.
1. Schowalter, Daniel N., “Virgin birth of Christ”, the Oxford Guide to the Bible, Oxford University Press, New York, NY, 1993, pg. 790
2. Sweeney, Marvin A., “Isaiah”, the New Oxford Annotated Bible, Fourth Edition, Oxford University Press, New York, NY, 2010, pg. 977-978
3. Schowalter, “Virgin birth…”, pg. 790
4. Vermes, Geza, the Nativity: History and Legend, Doubleday, New York, NY, 2006, pg. 47-48
6. O’Neil, Matthew, What the Bible Really Does (and Doesn’t) Say About Sex: the How, When, Why, and with Whom of Scriptural Prohibitions and Permissions, Pitchstone Publishing, Durham, NC, 2015, pg. 22
[Image: God the Father by Cima da Conegliano, c. 1515 / Public Domain]