The Immaculate Conception is a very biblical.
14 And the Lord God said to the serpent: Because thou hast done this thing, thou art cursed among all cattle, and beasts of the earth: upon thy breast shalt thou go, and earth shalt thou eat all the days of thy life. 15 I will put enmities between thee and the woman, and thy seed and her seed: she shall crush thy head, and thou shalt lie in wait for her heel. Genesis3;14-15
These verses are interpreted to be a prophesy about Mary and Jesus. Some say that this is a mis translation and it should say “He shall crush” but either way it does not matter. In order to have true enmity between the woman and the serpent or Satan, the Woman would have to be completely free of Satan. Sin causes us to be slaves of Satan and consequently she would have to be free of sin in order to have true enmity.
The second arguement is that Mary is the new ark of the Covenant. There are many instances in the bible where the writers are drawing comparisons between Mary and the Ark of the covenant.
Here are some examples
** 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: