The term Immaculate Conception refers to Mary being conceived without the stain or injury of Original Sin.
The term immaculate means clean, spotless, free from sin, free from fault, free from error, without blemish, spot or mark. Mary’s conception was this pure.1
This is proven when we look at the Annunciation, her role as the New Eve and her role as the true Ark of the Covenant.
Full of grace from her conception
When the angel appeared to Mary at the Annunciation, the angel said the following:
Hail, full of grace, the Lord is with you! – Luke 1:28
The angel did not say, “Hail Mary,” but “Hail, full of grace.” The angel did not identify her by her name, but by her title: Mary, full of grace.
This means that Mary, herself, was full of grace, and she was full of grace at the moment they met.
But, how could this be? Christ had not yet died and resurrected to give grace to mankind (Luke 24:46, Ephesians 2:16); Mary could not have done anything in her life to earn grace (Ephesians 2:8); and grace is only found in the soul of one who is baptized and cleansed of original sin (Romans 6:3-5, 1 Peter 3:21).
So, how was it possible for Mary to be full of grace when the angel met her if there was no way for her to acquire these graces?
The only answer, taught from the beginning of Church history, was that Mary was created full of grace without the stain of Original Sin from her conception. Her very being was made full of grace. In other words, her conception was immaculate.
There are two more reasons we know she was conceived immaculately: because she is the New Eve and because she is the Ark of the Covenant.
Mary, the New Eve, was created without sin like the first Eve
We know that Mary is the New Eve. If Eve was created without sin, then Mary, who is the New Eve, is also created without sin.
Further, if all of creation is created through Christ (Hebrews 11:3), and if Christ chose to create His first children without sin, it is not unreasonable to think He would create His mother, from whom He would acquire His flesh and blood, without sin.
Mary, the Ark of Covenant, is holy because of Who is inside of her
We know that Mary is the true Ark of the Covenant. The Ark of the Covenant carried the items that prefigured Christ. Mary carried Christ Himself. If the non-living Ark was considered so holy it was placed within the Holy of Holies, then the living Ark, Mary, must be that much more holier.
Consider that the God declared the wandering Israelites unfit to touch His alter in the desert because their presence would profane it (Exodus 20:26), and yet Mary was so holy she carried God within her. The degree of her holiness points to her being created in a way different from any other creature, full of grace from her conception.
Therefore, from the above, we can see that Mary’s conception was immaculate and that she was full of grace from her conception.
The Immaculate Conception
Mary is also titled as “The Immaculate Conception.” At the apparition at Lourdes to St. Bernadette, Mary said, “I am the Immaculate Conception.” She did not say she was immaculately conceived (though she is), but instead introduced herself as “The Immaculate Conception.”
St. Maximilian Kolbe wondered why this was for many years. He received the answer just before his arrest by the Nazis.1 (pg 51)
The Holy Spirit and the Immaculate Conception
St. Maximilian Kolbe came to understand that the Holy Spirit is the Immaculate Conception.
The Holy Spirit is the love that flows from the Father to the Son and from the Son to the Father.1 This love is immaculate because the love of the Holy Trinity, who He is, is spotless and pure.2 This love is also conceived from God to God.1
Therefore, we see that the Holy Spirit is called the Immaculate Conception because He is the pure spotless love that is conceived from God to God.
In another sense, the Holy Spirit is also the Immaculate Conception because He alone perfectly understands (conceives) the thoughts of God (1 Corinthians 2:11, Catechism 687), making His understanding of God the Immaculate Conception of God.1, 2
Mary and the Immaculate Conception
Now that we know why the Holy Spirit is called the Immaculate Conception, let us study why Mary is called the same. She does this for two reasons:
The first reason is that, when a husband and wife marry, the wife takes on the husband’s last name (she identifies herself by his identity). Because Mary is the spouse of the Holy Spirit, she now identifies herself by His identity: the Immaculate Conception.1 (pg 54)
The second reason is that the title, “Immaculate Conception,” actually applies to her being as well.
The Holy Spirit is called the uncreated Immaculate Conception because of the love that He is, the pure spotless uncreated love conceived from God to God.1 (pg 53-54)
Mary is called the created Immaculate Conception because she is the pure spotless life conceived from the Holy Spirit that has all the love of creation within her.1 (pg 53-54), 2 Specifically, she has all the love God has for creation in her son, Jesus Christ (John 3:16) and she has all the love that creation could have for God in her soul because her soul is full of grace by the Holy Spirit.
This why Mary called herself “The Immaculate Conception.”
To our great benefit, St. Maximilian Kolbe further discerned that when the uncreated Immaculate Conception met the created Immaculate Conception, that was the point at which God met man (God the Holy Spirit overshadowing Mary) and God became man (God the Son becoming human).1 As a result, the Holy Spirit meeting Mary is one of the most important turning events in human history.