The biblical portrait of Mary begins with the prophecy of the salvific mission of the Woman and her Seed in the book of Genesis and ends with the stunning vignette of the triumphant Woman Clothed with the Sun in the book of Revelation.
The truth about Mary and her role in salvation can come only from a full understanding of Scripture and the portrayal of Mary in Scripture. This full understanding comes from careful study of the two covenants between God and His people, the Old and the New. Mary is the bridge between the Old and the New Covenants. The two covenants are basic to the
divine plan of salvation and Mary's role in salvation history becomes apparent when we see that she is the living embodiment of fundamental themes in the Old and the New Testaments: as the Daughter of Zion, the Ark of the Covenant, the new Eve working with the new Adam.
To a great extent the loss of Mary among modern Christians stems from ignorance of the ancient insight that the drama of salvation begins in the book of Genesis with the prophecy of a new Adam and a new Eve and ends in the book of Revelation with the culmination of the battle between the serpent and the new Adam (Jesus) and the new Eve (Mary). This truth was accepted by all Christians until quite recently and even Martin Luther saw in Genesis 3:15 a prophecy of Jesus and Mary. Once the glorious role of Genesis and Revelation in the biblical revelation of the scheme of salvation was lost to view there was a corresponding eclipse first of Mary and then of Jesus. The first Christians and the Fathers looked to Genesis to understand Jesus and Mary and the message of salvation. The significance of the book of Revelation was understood only later because the Scriptures initially available to the early Christians were the Jewish Scriptures.
The story of salvation starts at the beginning of human history with Adam and Eve giving in to the temptation of the serpent and through their disobedience opening wide the doors of damnation and death for themselves and their descendants. At that crucial juncture God Himself announces that it is a woman and her seed who will do battle with the serpent and crush its head: "And the Lord God said unto the serpent, ... I will put enmity between thee and the woman, and between thy seed and her seed; it shall bruise thy head, and thou shalt bruise his heel." (Genesis 3:14-15).
By Mary's obedience, the new Eve gave birth to her seed, the new Adam, Who would "save his people from their sins". He was "Emmanuel", God with us, and she was therefore the "Mother of God" - by seeing her as Mother of God we are reminded too of His true humanity, His Adamness. If it was truly God Who was born with a human nature, He could not be generated by a human action - hence the Virgin Birth. In truly being the Mother of God it was unthinkable that Mary could be mother of anyone else - hence the doctrine of her perpetual virginity (and if she was thought to have had other children this would place the Virgin Birth in question as well). If Mary was truly to be the New Eve she could not be subject to the Original Sin brought about by the first Adam - and hence the doctrine of the Immaculate Conception brought about by the redemption won by the new Adam . Since the corruption of the grave came from Original Sin and the new Eve was truly the partner of the new Adam who reversed Original Sin she could not be subject to the consequences of Original Sin - hence the doctrine of the Assumption.