That Mary was (and, of course, we Catholics believe that she still is) full of Grace is clearly evident in Luke 1:28, when Gabriel addressed her as "Full of Grace"! The problem for many non-Catholic Christians is the idea that she was born that way and that she was sinless. But Mary had to have been literally filled with Grace because Christ is her Son -- and He is perfect!. She is more that some really cool, spiritual woman who acted as a surrogate mother for the Holy Spirit; she gave to Jesus His humanity in the same way that all mothers give to their children their humanity. He took from her His very Flesh and Blood! It was through her that our Lord "was made of the seed of David according to the flesh" (Romans 1:3). As Ireneus of Lyons asked in his Adversus haereses (ca A.D. 180), "...why did He come down into her if He were to take nothing of her?"
All Christians believe in saving grace and in sanctification. This being so, what is hard to believe about the idea that God sanctified Mary in her mother's womb, especially given that Mary bore Christ in hers? Can't the Awesome God Who overshadowed Mary so that she would conceive the Son be perfectly capable of preparing her from her own mother's womb to be a pristine vessel for such a glorious task? He created Eve without sin, would He not create His own Mother without sin, also? St. John the Baptist was filled with the Holy Ghost even from his mother's womb. His father, the priest Zecharias was told:
Luke 1:13-15
But the angel said unto him, Fear not, Zacharias: for thy prayer is heard; and thy wife Elisabeth shall bear thee a son, and thou shalt call his name John. And thou shalt have joy and gladness; and many shall rejoice at his birth. For he shall be great in the sight of the Lord, and shall drink neither wine nor strong drink; and he shall be filled with the Holy Ghost, even from his mother's womb.
-- and this is, of course, exactly what happened. In the same Gospel we see how St. John, in the womb of his mother Elisabeth, was filled with the Holy Ghost along with his mother when Mary visited:
Luke 1:41-44
And it came to pass, that, when Elisabeth heard the salutation of Mary, the babe leaped in her womb; and Elisabeth was filled with the Holy Ghost: And she spake out with a loud voice, and said, Blessed art thou among women, and blessed is the fruit of thy womb. And whence is this to me, that the mother of my Lord should come to me? For, lo, as soon as the voice of thy salutation sounded in mine ears, the babe leaped in my womb for joy.
If God can fill St. John with such grace in his mother's womb, why can't He do the same for Mary? And why wouldn't He?
The Ark of the Covenant in the Old Testament was adorned by two carved cherubim, symbols of God's glory, and on top of it sat the Mercy Seat, upon which goat's blood was sprinkled on the Day of Atonement -- the only day of the year (after Moses) that the High Priest (and the High Priest alone) could approach it in its Holy of Holies. Most importantly, the presence of God was over it. Touching this Ark -- just looking into it -- would kill a man. Powerful and holy indeed was this sacred vessel! And what did it contain? See Hebrews 9:4:
The Ark of the Covenant
-The word of God -- the stone tablets inscribed with the Decalogue
-Aaron's rod that "came back to life" and sprouted
-manna, the Heavenly bread
The Ark of the New Covenant, Mary
-The Word, Christ Jesus
-Our Lord, Who rose again on the third day
-The Savior, Who said " For My flesh is food indeed, and My blood is drink indeed. He who eats My flesh and drinks My blood abides in Me, and I in him. As the living Father sent Me, and I live because of the Father, so he who feeds on Me will live because of Me. This is the bread which came down from heaven--not as your fathers ate the manna, and are dead. He who eats this bread will live forever." (John 6:52-58)
St. Luke clearly wanted us to see Mary as the New Ark in that, inspired by God, he parallels many of his verses with those used to describe the Ark of the Covenant in the Old Testament. Compare, for example, Luke's words with 2 Samuel 6 below:
2 Samuel 6:2 And David arose, and went with all the people that were with him from Baale of Judah, to bring up from thence the ark of God, whose name is called by the name of the LORD of hosts that dwelleth between the cherubims.
Luke 1:39 And Mary arose in those days, and went into the hill country with haste, into a city of Juda
2 Samuel 6:9 And David was afraid of the LORD that day, and said, How shall the ark of the LORD come to me?
Luke 1:43 And whence is this to me, that the mother of my Lord should come to me?
2 Samuel 6:11 And the ark of the LORD continued in the house of Obededom the Gittite three months...
Luke 1:56 And Mary abode with her about three months...
2 Samuel 6:16 And as the ark of the LORD came into the city of David, Michal Saul's daughter looked through a window, and saw king David leaping and dancing before the LORD [His Presence over the Ark]
Luke 1:41 And it came to pass, that, when Elisabeth heard the salutation of Mary, the babe leaped in her womb; and Elisabeth was filled with the Holy Ghost:
In the Old Testament, the Ark of the Covenant, overshadowed by the the Spirit of God, was the instrument through which God came to dwell among men; in the New Testament, Mary, overshadowed by the Holy Spirit, is the instrument through which God came to dwell among men. She is the Ark of the New Covenant.
And here's a biggie: look carefully at Revelation 11:19-12:1. St. John tells us what he sees in Heaven: "And the temple of God was opened in heaven, and there was seen in his temple the ark of his testament: and there were lightnings, and voices, and thunderings, and an earthquake, and great hail. And there appeared a great wonder in heaven; a woman clothed with the sun, and the moon under her feet, and upon her head a crown of twelve stars [this woman, we are told later in chapter 12, is the one who brought forth the man child who would rule over the nations, ie, Christ].
Keep in mind, too, that chapter and verse divisions did not exist until the Middle Ages: what John says he saw is the Ark of the Covenant -- a woman. Really -- think about this: there is the Ark of the Covenant, lost for generations, in the Heavenly Temple! Then come the "special effects" -- lightning! Thunder! The very earth shakes! And there is the woman who brought forth the man child who who would rule over the nations... Mary, the pure and holy Ark of the New Covenant. [Note that the Woman of Revelation 12 is also a symbol of the Church, which has Mary for Her Mother; there is dual meaning here!]
