Immaculate Conception and something like it in all baptized Christians

Today's Gospel reading comes from that scene with Gabriel announcing the Incarnation to Mary. Why is that the reading for the feast of the Immaculate Conception. Because the Incarnation of Christ is the reason for the Immaculate Conception. In order to prepare the way for Christ, Mary must be made particularly ready to receive in her womb the Son of God. We who are baptized Christians are prepared similarly, but not in exactly the same way. My reflection on this goes thus:
  The Incarnation was a singular atomic event at the conception of Jesus in Mary's womb, and likewise, that preparation to receive the incarnated Jesus was a singular atomic event of the Immaculate Conception of Mary who was preserved from original sin at the moment of her conception in the womb of her mother, Anne. On the other hand, the conception of Jesus in us is a gradual, unfolding event. We are first born again at baptism as a new creation, but Jesus is not incarnated in us completely. Rather, as we cooperate with God's grace, our flesh is transformed gradually into Christ's body. The more we think, speak and act as the Holy Spirit moves us, the more completely Christ is incarnated in us, culminating in the resurrection of the dead.
  I sure hope this makes sense. Anyone?