As we know, Baptism is the gateway to the rest of the Sacrament.
One must be baptized in order to receive the rest of the Sacraments.
If that can be said of Baptism, so too can be said of the mystery of the Incarnation.
At the Annunciation, the angel Gabriel told Mary that the Holy Spirit will come upon her and the power of the Most High will cover her.
The child that she will conceive in her womb will be holy and will be called Son of God.
God becoming man in the womb of Mary, or the Incarnation, is a great mystery that requires faith to accept and understand.
Those whom God has chosen and called and given the faith will be able to accept the mystery of the Incarnation, just as Mary was chosen and called and she responded.
In accepting and believing the mystery of the Incarnation, we then journey with Mary into the life of Jesus, and we will see the mystery of salvation unfold in the suffering, death and Resurrection of Jesus.
When we can accept and believe in the mystery of the Incarnation, then we will also be able to believe that with God, nothing is impossible.