Blessed Pius IX in the bull Ineffabilis Deus defined “the doctrine which asserts that the most Blessed Virgin Mary, from the first moment of her conception, by a singular grace and privilege of Almighty God, and in view of the merits of Jesus Christ, Saviour of the human race, was preserved free from every stain of original sin, is a doctrine revealed by God and, for this reason, must be firmly and constantly believed by all the faithful.”
Now, in dealing with Catholic holidays and concepts many are misinformed, confused or ignorant. I had a good man and professor for medieval history, who made the momentary mistaken substitution of the Incarnation (Virgin Birth) with the Immaculate Conception. I had a professor of ancient history, who was, confused over the Epiphany. Sometimes a kid in second grade catechism knows more than a doctorate.
Our current pope has announced a plenary indulgence for pilgrims, who travel this year, to Lourdes, France. It has been one hundred fifty years since Mary appeared to St. Bernadette Soubirous there, and identified herself as the Immaculate Conception.
There is a second option:
"If between February 2, 2008 ... and February 11, 2008, Feast of the Blessed Virgin Mary of Lourdes and 150th anniversary of the apparition, they visit, in any church, grotto or decorous place, the blessed image of that same Virgin of Lourdes, solemnly exposed for public veneration, and before the image participate in a pious exercise of Marian devotion, or at least pause for an appropriate space of time in prayer and with pious meditations, concluding with the recital of the Our Father, the Profession of Faith, ... and the invocation of the Blessed Virgin Mary.""In Adam's fall, we sinned all", is a concise definition of original sin. This is a stain on our souls born on us all, save Mary. Man was created wholly good, as were the angels, but by choice (free will) our nature was singed.
Calvinists misstate and misunderstand this. Man is not a priori evil. All that God had created he created good.* Man's original nature was good. In our original parents we fell, but in a Man born from woman, we are redeemed. One third of the angelic host also fell, previous to us, before our universe began. Their leader, goaded and led us to that fall,† and he is the enemy of that woman who bears the Redemption of the world.‡ By God's gracious act, that woman was conceived without the taint of original sin.§ We still have choices.
What was this original sin of Satan and our parents? A form of egotism and delusion, where it is presumed of us, to be like God. This egotism is a selfishness, a pride betaken that is not appropriate, contrary to the humility that belongs to us. And to correct this God humbled himself to be born amongst men to redeem us. God so loved the world and us that he created it and died for us.ll We, his creations, should have this sort of love, we fell because we coveted what was not ours, we did not love, we desired. We can not be equal to the Creator. Satan's rebellion was also akin to this, and he wished us to follow.
*Genesis i.10 And God called the dry land, Earth; and the gathering together of the waters, he called Seas. And God saw that it was good.
12 And the earth brought forth the green herb, and such as yieldeth seed according to its kind, and the tree that beareth fruit having seed each one according to its kind. And God saw that it was good.
18 And to rule the day and the night, and to divide the light and the darkness. And God saw that it was good.
21 And God created the great whales, and every living and moving creature, which the waters brought forth, according to their kinds, and every winged fowl according to its kind. And God saw that it was good.
31 And God saw all the things that he had made, and they were very good. And the evening and morning were the sixth day.
†Genesis iii.1 Now the serpent was more subtle than any of the beasts of the earth which the Lord God made. And he said to the woman: Why hath God commanded you, that you should not eat of every tree of paradise?
2 And the woman answered him, saying: Of the fruit of the trees that are in paradise we do eat:
3 But of the fruit of the tree which is in the midst of paradise, God hath commanded us that we should not eat; and that we should not touch it, lest perhaps we die.
4 And the serpent said to the woman: No, you shall not die the death.
5 For God doth know that in what day soever you shall eat thereof, your eyes shall be opened: and you shall be as Gods, knowing good and evil.
6 And the woman saw that the tree was good to eat, and fair to the eyes, and delightful to behold: and she took of the fruit thereof, and did eat, and gave to her husband who did eat.
‡Genesis iii. 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.
§Luke i. 28 And the angel[Gabriel] being come in, said unto her: Hail, full of grace, the Lord is with thee: blessed art thou among women.
llJohn xv. 13 Greater love than this no man hath, that a man lay down his life for his friends.