Although the Immaculate Conception is not found in the Sacred Scripture in any literal sense, the Church has arrived at the teaching by drawing out the implications of many texts which speak of her and her role in salvation.
In Genesis 3:15, immediately after the sin of Adam, God revealed His plan of salvation to be accomplished through the fidelity of a man and a woman, just as our fall occurred through the infidelity of a man and a woman.
“I will put enmity between you (Satan) and the woman, and between your offspring and hers; He will strike at your head, while you strike at his heel.”
The offspring of Satan is sin; therefore, the Woman and Her Seed will be without it, completely opposed to Satan and his offspring. Thus, we see in the very first announcement of God’s plan for salvation that He intends to keep Mary free from sin so that Jesus would assume a pure human nature.
The New Testament also shows the truth of this role. In the Gospel of John, the Apostle reports two significant occasions when the Lord calls His mother “Woman,” connecting her to the Woman of Genesis 3:15. First at the beginning of His ministry (John 2:4), and then again at its consummation on the Cross (John 19:26)—the moment of Satan’s apparent triumph. He likewise speaks in Revelation 12 of the “Woman clothed with the sun” who gives rise to the Child destined to rule the world.
We get further confirmation from Luke 1:28, which records the angel addressing Mary as “full of grace” (“perfected in grace”). And again, in 1:41-44, when Elizabeth greets her cousin Mary,
“Blessed are you among women, and blessed is the fruit of your womb! And why is this granted to me, that the mother of my Lord should come to me? For behold, when the voice of your greeting came to my ears, the child in my womb leaped for joy.”
The Church very early, therefore, recognizing the parallels between the Fall and the Redemption began referring to Mary as the New Eve, and over the centuries to draw out all the implications of this role of grace––the reality of which began with her preservation from the sin of Adam, through the Immaculate Conception.