“Let us reject those who say that the Savior’s birth was the accomplishment of a man and a woman; those who dare to say that he was born of Joseph and Mary, solely because it is written: “And he took (her as) his wife” (Mt 1:24). Let us remember Jacob, who before taking Rachel, said to Laban: “Give me my wife” (Gen 29:21). Just as she was called Jacob’s wife before the marriage celebration solely because promises had been exchanged, so also Mary was called Joseph’s wife because she was betrothed.
Note how precise the Gospel is when it says: “In the sixth month the angel Gabriel was sent by God, to a town of Galilee named Nazareth, to a virgin betrothed to a man named Joseph” (Lk 1:26-27), and so forth. Again, when the census was taken and Joseph had to enrol himself, what does Scripture say? “Then Joseph went up from Galilee also, to register together with Mary, his betrothed spouse, who was with child” (Lk 2:4-5). And even though Mary was with child, it does not say, “his wife”, but “his betrothed spouse” Indeed, God- says Paul-sent his Son, not born of a man and a woman, but of a woman (cf. Gal 4:4) only, that is, of a virgin. We have shown that a virgin is called a woman. For from a Virgin was born the One who makes souls virgins.”Cyril of Jerusalem, Catecheses 12, 31-32; PG 33, 764-65
Part of believing that Jesus is God and a perfect man is believing in Virgin Mary’s virginity. St. Cyril explains what the scripture reveals about Mary’s virginity after giving birth to Jesus. Christians, as St Mary, should know that God is ready to involve us in his work, as long as we consent to his work. And through His grace working in us, our human state becomes virgin ,pure, as was St. Mary.
Gambero, L., 1999. Mary and the Fathers of the Church 1st ed. Translated by Buffer, T., San Francisco: Ignatius Press. p. 139-138.