Some Protestants who know no better imagine that the Immaculate Conception is the description that the Church of Rome gives to the Virgin Birth of the Lord Jesus Christ. His was indeed an immaculate conception, a conception and birth totally without sin. But when Rome uses this term she has an entirely different birth in mind. According to Pope Pius IX, it is "a doctrine revealed by God" that Mary the mother of Jesus was born without sin. Here is the papal decree that established this dogma as a doctrine to be believed on peril of losing your soul:
We declare, pronounce and define that the Most Blessed Virgin Mary, at the first instant of her conception was preserved immaculate from all stain of original sin, by the singular grace and privilege of the Omnipotent God, in virtue of the merits of Jesus Christ, the Saviour of Mankind, and that this doctrine was revealed by God, and therefore must be believed firmly and constantly by all the faithful.
This is what Rome means by the Immaculate Conception: Mary was conceived and born entirely without sin. According to the Pope, when he established it as official dogma in 1864, this is a doctrine revealed by God. "Where?" you may ask. Certainly not in the Scriptures, where Mary rejoiced "in God my Saviour." Only sinners need a Saviour and Mary needed a Saviour. The dogma was unknown in the early church and for centuries after Mary's death. Augustine, whom Rome pretends to revere as one of the greatest of theologians and a saint, spoke of Mary's flesh as "the flesh of sin" and stated that Mary, springing from Adam, died because of sin. So, where did God reveal that Mary was conceived without sin? The Pope claims that He revealed it in the Tradition of the church, which the Pope officially recognized in 1864. Of course, since it was unknown in the early church, the dogma of Mary's Immaculate Conception was not a divine revelation but a late human innovation.
Rome espouses it because she has evolved an entirely anti-Christian system of Mariology and, indeed, Mariolatry. Not content with decreeing that she was born without sin, a later Pope, Pius XII, decreed in 1950 that she had been assumed bodily into heaven. It appears that in every possible detail, Rome is determined to create in Mary a replica of the Saviour, making her His equal in a sinless birth and a bodily Ascension into heaven.
But it is all a gross deception. The Pope has absolutely no right to establish Christian doctrine. To assert otherwise is to brand him as an antichrist. There is only One who was born without sin and that is the Lord Jesus Christ. He is emphatically called "the Holy One," "the righteous One," and the "just One." Mary was a good and great woman but she needed to be saved from her sin-and praise God, she was. Jesus Christ, on the other hand, needed no sacrifice for sin, for He was sinless, and being sinless He wrought a perfect obedience in life and in death to expiate our guilt and propitiate God's wrath against it.
As I said, the Immaculate Conception is a gross deception. Mary was born in sin; she was saved from sin; she died and was buried; her body corrupted like everyone else's. She is utterly incapable of doing anything at all to save or help sinners. Only God's Christ can do that.