God clearly tells us in His written word that all of humanity is sinful and Mary is part of this sinful humanity.
God explicitly tells us in his written word that Jesus was “sinless” since Jesus is the unblemished Lamb of God who takes away the sins of the world. In other words, we must know that God did in fact send his Son into the world to atone for our sins and reconcile us with the Father. Jesus replaced the unblemished lamb at Passover in the Judaic tradition. But the Spirit of the Word speaks for Christ to his Church and implictly tells us in the written word that Mary was sinless in virtue of her Divine Maternity. She bore the unblemished Lamb of God as the pure and undefiled ark of the Old Covenant carried his Word. Luke, who typifies Mary as the Ark of the New Covenant, portrays the mother of our Lord as pure and undefiled: sinless. He need not explicitly write that Mary was “sinless”, for our Blessed Mother was not fashioned by God to die for our sins. Her divine maternal role was collaborative, which required that she be pure and spotless in virtue of her divine offspring.
The Angel went to her and said, “Hail, full of grace. The Lord is with you.”
Luke 1, 28
"But why am I so favoured, that the mother of my Lord should come to me? As soon as ‘the sound of your greeting’ reached my ears, the child in my womb leaped for joy?
Luke 1, 43-44
As the ark of the Lord was entering the city of David, Michal daughter of Saul watched from a window. And when she saw King David leaping and dancing before the Lord, she despised him in her heart.
2 Samuel 6, 16
Moreover, to completely undo the fall of mankind brought about by Eve’s seduction of Adam, Mary had to be the antitype of Eve. Woman contributed to the fall, so God ordained that woman should contribute to man’s redemption. Mary, the free Woman of Promise, prefigured by Sarah who opposes the slave Hagar, could not have undertaken this vital part in the economy of salvation if she were under the slavery of sin and on common ground with the serpent who seduced Eve. Eve was created sinless before she succumbed to the word of the serpent. Luke perceives Mary as the New Eve as well, so he couldn’t have believed she were sinful.He alludes to her as one who heard the word of God and kept it (cf.11:28).
Mary said, “Behold, I am the handmaiden of the Lord. Let it be done to me according to your word.”
Luke 1, 38
"I will put enmity between you and the woman, and between your seed and her seed. He (She) will crush your head, while you lie in wait at his (her) heel.
Genesis 3, 15
Then Uzziah said to her, “Blessed are you daughter, by the Most High God, above all the women of earth; and blessed be the Lord God, the creator of heaven and earth, who guided your blow at the head of the chief of our enemies.”
Judith 13, 18
“Most blessed are you among women, and blessed is the fruit of your womb. Blessed are you who believed that what was spoken to you by the Lord would be fulfilled.”
Luke 1, 42, 45
Scripture is not the sole medium of Divine revelation. Jesus founded his one universal Church on Peter and the Apostles to serve as the custodian of the divine truth. This truth is mediated by Sacred Tradition, alongside Scripture, and explicitly taught by the teaching authority (Magisterium) of the Church. Dogma acts to make explicit what is implicit in Scripture and constantly preceived in the life of the Church through the centuries by the activity of the Holy Spirit. The Immaculate Conception and the personal sinlessness of Mary belong to the deposit of faith: Scripture and Tradition. Scripture alone is formally insufficient as a medium of Divine revelation, since Scripture originates from Tradition. The two mediums of Divine revelation compliment each other. Jesus founded a Church. He did not publish a Bible. The Church takes precedence in communicating the Word of God.
“And thus also it was that the knot of Eve’s disobedience was loosed by the obedience of Mary.”
Irenaeus (A.D. 180)
“He was formed of incorruptible wood. For by this is signified that His tabernacle was exempt from putridity and corruption.”
Hyppolytus (A.D. 235)
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“Mary, a Virgin not only undefiled but a Virgin whom grace has made inviolate, free of every stain of sin.”*