They certainly confirm that dogma although of themselves they could not be regarded as an adequate and explicitly biblical proof of it. More telling would be God's promise in Genesis 3:15, declaring that He would put enmity between Satan and the woman. The early Christian Fathers interpreted the promised woman as a new Eve, as sinless as Eve herself was before the first sin; and the Church has defined the doctrine that, through the anticipated merits of Christ's redemptive work, Mary's soul was preserved from the contagion of original sin. As grace is the opposite of sin, the angel's salutation of Mary as "full of grace" brought out the radical opposition - the "enmity" - between the promised woman and Satan. Never for a moment was Mary, the Mother of Christ, under the actual dominion of Satan, as she would have been had she at any time been subject to sin. The Anglican Dr. E. L. Mascall, at a London conference with Eastern Orthodox theologians in 1948 - the discussions being published later in a book entitled "The Mother of God" - declared his own firm belief in the doctrine of the Immaculate Conception, saying that if Mary was to be a worthy dwelling-place for the Divine Word she would have to be pure in every respect, which includes freedom from original sin by a special intervention of the grace of God. And he drew from the Orthodox Professor G. Florovsky the admission that before Pope Pius IX defined the doctrine in 1854 a number of prominent Eastern Orthodox theologians had upheld the doctrine.
Do the angel's words to Mary: "Hail, full of grace" (Lk., 1:28) prove the dogma of the Immaculate Conception?:http://www.radioreplies.info/radio-replies-vol-5.php?t=9