Aquinas says, "But she would not have been worthy to be the Mother of God, if she had ever sinned. First, because the honor of the parents reflects on the child, according to Prov. 17:6: "The glory of children are their fathers": and consequently, on the other hand, the Mother's shame would have reflected on her Son. Secondly, because of the singular affinity between her and Christ, who took flesh from her: and it is written (2 Cor. 6:15): "What concord hath Christ with Belial?" Thirdly, because of the singular manner in which the Son of God, who is the "Divine Wisdom" (1 Cor. 1:24) dwelt in her, not only in her soul but in her womb. And it is written (Wis. 1:4): "Wisdom will not enter into a malicious soul, nor dwell in a body subject to sins."
-A8
Well, your first appeal is to the word of Augustine. He was a fine Christian, but his words are not given by inspiration. You then appeal to a book in the Apochrypha (sp?), a book certainly not accepted in all Bibles, nor in the Jewish scriptures, books which are generally fine as literature but not generally accepted as the inspired Word of God.
Much of what I see posted here argues from logic. Logic is fine, but it does have its limitations. To illustrate, Luigi Barzini in his book "The Italians" (published 1964) tells this story: a very wealthy Sicilian made a vow to make a pilgramage by foot to Jerusalem. As he contemplated this he realized that he would be absent for a very long time. So, he calculated the distance overland from the mainland of Italy to Jerusalem and then measured the distance around his estate. Dividing the greater distance by the smaller distance, his logic said that he would fulfil his vow if he walked around his estate that many times.