Ihe Immaculate Conception (celebrated sometime in December before Christmas) is the celebration of the conception of the Blessed Virgin Mary. It is important because according to the Catholic Church, Mary was born without original sin (she never sinned during her life). The woman that was to bear the Savior (Jesus Christ) had to be pure, meaning that she was a virgin and without sin.

The previous answer is correct and does not contradict the bible as the subsequent commentator suggests. This is why: Pope Pius IX stated in his dogma of 1854 that "the most Blessed Mary was, from the first moment of her conception, by a singular grace and privilege of Almighty God and by virtue of the merits of Jesus Christ, Saviour of the human race, preserved immune from all stain of original sin." This states that Christ redeemed all human beings, including Mary although in her case it was done differently. According to the medieval Franciscan theologian, Duns Scotus (1266-1308) Christ's role was to mediate for all men, and that to do so He must have been born of a pure mother. Since this mother was also mediated by Him, then His mediation would be to make her immaculate which would also facillitate His birth. This does not contradict the Bible in that subsequent to Adam and Eve's fall from Eden, all men are born with Original Sin. In Mary's case, Christ removed her sin, as we now all have thanks to His sacrifice. In our case, this is through baptism. As Mary was His mother, hers was removed before birth, hence the title 'Immaculate Conception'. Another biblical point to note is what it means to be human. There are several references in the Bible to Mary's being an immaculate conception. These alone are not explicit, but together form the basis of Catholicism's belief. Briefly these can be found in Gen 3.15, Luke 1.28 and Luke 1.42 especially if you look at the original text. An example of where the translation may obscure the meaning can be seen in the Luke 1.28 extract "full of grace". This should more accurately say "you who have been, and remain, filled with the divine favour". Also, if Christ is the new Adam, and as such trancends him; and Mary is the new Eve...she should transend Eve. As Adam and Eve were both immaculate (being 'born' before Original Sin) for Mary to transend Eve, she should also be free from this sin. Another point to note is that only Adam and Eve are genuinely "human beings". We are "fallen human beings" as a consequence of Adam and Eve's sin. Since Christ is both God and Man, He has to represent both conditions so he was 'fathered' by the divine Holy Spirit. But He had also to be born human, not fallen human, as this was not God's original creation (as in Adam and Eve). To be born as the man that God originally created, Jesus must be born of a 'pure' mother, also clean of original sin, just as Eve. As Cardinal Newman states "none can bring a clean thing out of an unclean". So God saw fit to make Mary as He originally intended. To re-itterate, the Bible does not say that everyone is born with sin, as Christ was not, nor was Adam and Eve. This was the original actual state of man and one that was granted to Mary through the grace of God to enable Jesus to be born Man, and God.

The Immaculate Conception is a belief the catholics have. In 1854 Pope Pious IX said that Mary was born without "original sin". On the pretended ground that she was born without a taint of sin, that after Christ death she was miraculously taken up to heaven, and that she assist Christ in the work of redemption. Her sinnlessness is termed by Rome "Immaculate Conception". Her taking up to heaven is "Assumption of Mary", so I guess her assistance to Christ should give her the title "Coredemptorist". It was on December 8th, 1854 that Pope Pius IX. Such a fact that enthrones Mary beside Christ and declares her to be a saviour more compassionate than He, reveals a serious defect in a church which claims to be infallible. If the doctrine were true what a loss the members of the Church of Rome must have sustained through ignorance of it for the last 12 centuries. The whole Word of God teaches the contrary, even as Paul declares all of sinned and fall short the glory of God. Mary own language confirms that she was a sinner when she said " My spirit hath rejoiced in God my SAVIOUR". If she was sinless then why would she need a saviour. The teaching was unknown in the apostilic church, and in the writings of the first five centuries it is never once mentioned. Not one great name can be quoted for it during the first 11 centuries. On the contrary, no fewer than 14 popes oppose it.

Simply put, the Immaculate Conception celebrates the conception of the Virgin Mary (not Jesus) without original sin. That means that even from the moment of conception, Mary was not meant to be prone to sin as most humans are thanks to Adam and Eve. Mary, by nature, did not have the potential to sin, as part of God's plan. (A sinner can't give birth to the Son of God.)

The immaculate conception is when the angel, Gabriel, came to Mary, and asked her to be the mother of Jesus, to birth him. and Mary conceved Jesus, as a virgin. she was the mother of Jesus. and God asked her to do this, b/c she was free from every sin, including originle sin, which everyone {except her} is born with, she was the mother of God.