Before I respond to the Catholic blither and blather of Mary's reproductive prudery, let's survey what it is Catholics believe on this count.
First, Mary was a virgin before, during, and after Jesus' birth. Second, after Jesus was born, Mary never engaged in sexual congress with her husband, Joseph. Third, Mary's perpetual virginity is distinct from the Immaculate Conception of Mary; the former refers to Mary's inconsummate marriage to Joseph, the latter to Mary's being born into the world without the stain of original sin. And finally, fourth, Mary's virginal status means that Jesus had no siblings. While being an obvious point, it is important to note number four because it provides a ready-steady defense for the use of the words "the brothers of Jesus" (Matt. 13:55; Mk. 6:3) to allegedly mean "cousins of Jesus".
If the gospel accounts of Jesus' arrival in this world are true, then there is no difficulty believing that Jesus' mother was a virgin before his birth, and during his birth. It was customary of Mary's time -- and is even sensibly encouraged today -- to abstain from sexual intercourse before marriage. Mary was betrothed (i.e., engaged, to use modern terminology) to Joseph when she became pregnant with Jesus, which, to Joseph, appeared as infidelity until he was reassured by an angel that all was well, and that Mary was pregnant by God's doing.
This in itself seems like a peculiar infidelity that God would impregnate another man's wife (I think Zeus was prone to the same misgivings, so no surprise a similar motif would show up in a Hellenistic culture). Leaving that aside, however, if it was that Mary was born without sin, why couldn't God simply have used Mary and Joseph's eventual union to create another sinless person, but this time one that also happened to be God? Afterall, he created people from dirt; I'm fairly certain he could funnel himself through an egg.
All of the above notwithstanding, unless Mary remained betrothed to Joseph forever after, that is, unless Mary and Joseph together decided they would never get married but just live together raising Jesus, it seems unlikely, even supremely implausible that Mary remained a virgin after Jesus' birth. Two things come to mind at this point:
- Mary and Joseph were religious Jews, and so, would not have lived together as a couple without being married; not unless they wanted to be stoned to death (recall the historical time and prevailing religion) for being considered fornicators;
- It has always been the sexual act that seals a marriage, that makes the covenantal bond between two people and the God/gods they are loyal to.
- Mary and Joseph were witholding from each other, even knowing that at least one of them was desirous. This is a sin (see 1 Cor. 7:5) because it invites temptation into the marriage, and should only be done for a limited time; time enough for prayer and fasting, and then they were to enjoy marital bliss again.
- If it was sinful to withold from each other, then Mary's immaculate status is negated because she would've been sinning to enter a permanent, sexless marriage where one or both of the people involved would be sexually ungratified and desirous.
There is a direct relationship between Mary's assumed lack of original sin, and the Catholic claim that she was/is ever a virgin. The doctrine of original sin found its first expressions in the writings of Irenaeus, bishop of Lyon, when he was arguing with Gnostics. But the champion of the doctrine of original sin, however, was Augustine, bishop of Hippo. Augustine reasoned that
original sin was both an act of foolishness (insipientia) and of pride and disobedience to God of Adam and Eve. He thought it was a most subtle job to discern what came first: self-centeredness or failure in seeing truth. The sin would not have taken place, if satan hadn't sown into their senses "the root of evil” (radix Mali).
This in itself does not make the sexual act wrong in Catholic theology. However, because Mary was to be the bearer of God himself, there could be no taint of sin in her. Hence Mary's parents' copulation, somehow, didn't transmit a wounded nature to Mary (how convenient, yet, sadly, entirely presumptuous). Mary was, it is supposed in Catholicism, therefore perfect in her human nature. Thus for Mary to engage in coitus with Joseph would imply the possible transmission of human sinfulness to any offspring copulating may produce. Since God had housed himself in Mary's womb, any post-Jesus children would be (conspicuously) bad, because apparently God and people shouldn't intermingle -- which brings up a whole other set of issues. For example, a smattering of gnosticism. But I digress...
Before moving on to my last point, I will review, in short, the gist of my first three points:
- Mary would not have lived in a false marriage arrangement because this would implicate Mary and Joseph on the grounds of sexual sin: the surrounding community would've viewed a couple living together, and having a child together out of wedlock, as fornication.
- Mary's blameless and perfect nature would be blatantly stained by purposefully, and knowingly entering into a sexless marriage where her weaker, imperfect husband, Joseph, would burn after her with lust; i.e., Mary would've purposefully been tempting Joseph to sin.
- Mary's ever-virgin status, when distilled to its constituent elements, constitutes a form of gnosticism: she could not have copulated with one who bears the stain of original sin because her womb held the son of God; the perfection of God and Mary could not intermingle with the imperfection of a man.
And this, in itself, begs an obvious question. If it is true that Joseph had enjoyed a previous marriage, and then entered into a marriage with Mary, why would he want to give up one of the specific pleasures marriage allows: sex? Unless it can be argued from silence -- as assuredly Joseph's possible previous marriage is an argumentum ex silentio -- that Joseph was done with coitus funness when he set his eyes on Mary, there's nothing to support the notion that Joseph would willingly enter into a sexless marriage. At the same time, to give credit where it's due, there's nothing to support the notion that Joseph would not enter into a sexless marriage. In either case, we have absolutely no evidence at all to conclude on the virginal status of Mary, and Joseph's willingness or not to entertain an inconsummate marriage.
In conclusion, I think that the notion of Mary's perpetual virginity is purely a fabrication. Yes, many people have believed it for a good long time. However, the duration of a belief is no argument for its validity. Many people believed that the earth was flat for quite some time, but that is clearly not the case. From the reasons given by the Catholic church for Mary's eternal virginity, I have reflected some practical conclusions that show the weaknesses in the expectation that Mary was inconsummate in her marriage to Joseph. I could go on drawing further conclusions from the beliefs set out by Catholics, but it seems sufficient to say that Mary's constant virginity is a proposition based in silence, that when examined in a little detail becomes self-contradictory, disregards Occam's razor, highlights Catholic antisexualism, and therefore has no basis in reality.