First, I must make it clear that I see the Holy Days as having the same sacramental value as our own Baptism.  When we take the time to meditate on the very mysteries presented to us on the Holy Days, God imparts the grace of that particular mystery into our lives and hearts.  Through the Holy Days, we live the mysteries of the faith and claim those mysteries in our lives.  The Life of the Body of Christ on Earth must mirror the lives of Jesus and Mary.
Secondly, the Advent would not be possible without the Immaculate Conception of Mary.  The Apostle Paul calls Jesus the new Adam, and says that all Christians are a new creation of God, "old things pass away, and behold all things become new (2 Cor 5:17)." 
In the creation story in Genesis, we are told that God created man in its image, and then we are told that Adam and Eve sinned through eating the Fruit of the Knowledge of Good and Evil.  Before that, Adam and Eve were created in the image of God.  God is unity.  "Shema Israel, Adonai Eloheinu, Adonai Achad."  "Hear O Israel, the Lord our God, the Lord is Unity (Deut 6:4)." 

The reality of Adam and Eve was one of the unity of God.  When they ate of the fruit of the Tree of the Knowledge of Good and Evil, their perception of the world changed.  No longer did they see the Unity of God in all things, but they saw the world in terms of dualism: us and them, this and that, good and evil.  The problem of evil enters into the world. 

Now we either see everything as part of an essential oneness (which often overlooks individuals and turns to evil), or we see the obvious separateness of the world (which often overlooks commonality and leads to anarchy and evil).  We are mired in this to the point that all we can see is either oneness or duality.  This "fall from the Garden" occurs in all of our lives.  We often call it the end of innocence.
The Immaculate Conception begins to turn the creation upside down.  This is the moment God begins the new creation.  In Genesis, we read that God created Adam from the earth, and then created Eve from his side.  With the Immaculate Conception, God re-creates Mary the woman, separating her from the previous creation.  She becomes the New Eve: the new Mother of all living. 

At Lourdes, when our Lady was asked by St Bernadette, "Who are you?"  Our Lady replied, "I am the Immaculate Conception."  Now this is very important.  She did not say "I am the product of the Immaculate Conception," she said, "I am the Immaculate Conception."  Why?  She is the Mother of the new creation.  She is the beginning.

When the Archangel announced that Mary would bear the Son of the Most High, he told her that the Spirit of God would overshadow her.  Behold, a Virgin conceived.  Why?  This is the opposite of the first creation.  Mary the new Eve was created anew through the Immaculate Conception, and Jesus, the new Adam is created from her side, or more specifically, in her womb.
Now, the Fall from the Garden can be undone.  The fall immersed us in a world of duality, and that cannot be undone by the contrast of unity with duality.  Instead, God demonstrates the Nonduality of the world through paradoxes.  The Mother of God will give birth to her Creator.  The Virgin will be a mother.  The world is redeemed through the execution of an innocent man as a criminal.  The teachings of Jesus are full of such statements:  Those who mourn are comforted, the meek shall inherit the earth, the first shall be last, and so on. 

In the advent, we turn around to see the Nonduality of God where the unity and the individuality of the world are seen to be true simultaneously. 
This Holy Mystery is not a one-time event.  At our Baptism, the Spirit of Christ is conceived in our heart.  Just as Mary brought Jesus into her world, we bring Jesus into our own.  During Advent, we do not only commemorate an event that happened two thousand years ago, we also remember that Christ has been conceived in our heart.  In this time, we remember that the mission of the church is as Paul said, "My little children, for whom I am again in the pain of childbirth until Christ is formed in you (Gal 4:19)."
This is my view of Advent.  I humbly offer it to you so you will better understand my faith and me.
May the Love of God be with you,