Virgin Mary not a Virgin?

[FCEGM]

Can we go over why it is important that she IS a virgin?

It is important that she be a virgin before the conception of Christ Jesus because it demonstrates that God the Father through the power of the Holy Spirit is the only Father of Jesus.

As to why it is important that she remained a virgin during and after His birth, this article addresses it well:

. . . the virginal birth of Christ points to a miraculous conception (that His Father by Nature is God, not man) by the Holy Spirit (indicating the Trinity of Divine Persons); that Mary had no more children is just one indication that Christ Jesus is different in some essential way from all other humans. If she had had other children there would be absolutely no reason to think Jesus was any different from those siblings in His origin, i.e., that He was God the Son become Man. Thus the Perpetual Virginity safeguards the specialness of Jesus as born miraculously, which safeguards His special conception, which manifests His Eternal Pre-Existence. So there IS a “logic” to the Incarnation of God as Man.

The Man Jesus is claimed to be a Divine Person, always having existed eternally with His Father, Who descended to become a man. His conception must manifest this (He cannot have a human father). Thus the miraculous conception by the Holy Spirit overshadowing Mary and making from her flesh a Conceptus. Mary’s virginity guarantees that He has no human father (St. Joseph being a foster father and guardian) but only a Divine Father.

There is also the religious distinction between the sacred and the profane or ordinary. Something sacred is set apart from the ordinary only for Divine use or purpose. For example, one does not take the chalice used at Mass and use it for ordinary meals to drink soda from. Mary’s womb is the sacred “chalice” containing the Divine Humanity of God the Son; her womb is to be used only for that Divine purpose – because of the Holiness of God (God in the Judeo-Christian understanding is different from His Creation; and Holiness is the attribute of this difference). So there is a religious “logic” of the sacred as different from the profane, i.e., the creaturely element set apart only for Divine use or purpose, therefore never for ordinary use. It does not mean the ordinary is dirty or evil; the ordinary is good but not Divine. The sacred is taking something away from ordinary use and consecrating it for the Divine. That is why God would change the order of things for the unique Incarnation of His Divine Son. . .

bringyou.to/apologetics/a82.htm