“Mary, Mother of God”—Now that's a title that Christians had officially given Mary, mother of Jesus, in the 5th century as a result of the Council of Ephesus which dealt with the Nestorian heresy. More than a millennium later, years after the Western Schism that was called the Protestant Reformation, some Christians accuse the Catholic Church of deifying Mary, a mere creature of God.
The Catholic Church dedicates the last day of the Christmas Octave to Mary with the title of “Mother of God” not because we have deified her but because we want to glorify God, who has graced her with the role of being the mother to His Son. The title actually protects the integrity of the personality of Jesus the Christ. The Council of Ephesus affirmed that Jesus is only one person with two Natures. A woman gives birth to a person, not to a nature. Nestorius had claimed that Mary was "Mother of Christ" and not "Mother of God". This, in effect, splits Jesus into two persons. Jesus does not have a split personality. Thus Mary cannot be said to be only mother of Jesus the Man and not Jesus, the second person of the Holy Trinity.
I have started a reflection on today's feast and have digressed to give a brief account of one of the Christological doctrines. (I think Mr. Tim Staples does a better explanation than me here.) Let me get back to the reflection.
We celebrate this feast because we want to glorify God for showing us His willingness to fill His creatures with grace. Although we hear that Mary is highly favoured in the Gospel, God does not have favorites. (Please see Luke 1:28. Being highly favoured and being a favorite are two different things.) He wants all of us to be saved. That is why he announced the birth of Jesus to the shepherds and the shepherds, in their turn, told others. In the Gospel today, we notice that people came to know about this significant birth. Mary, who has been given a significant mention by the angels, did not become arrogant or proud. Instead, she quietly kept all that had happened in her heart, pondering over them (Luke 2:19).
I believe that God wants us to look at the gifts and graces He has given us. We must be grateful for them and humbly accept them. The good news is that He is ever willing to grace us. Every gift we have had is not something that we deserved. Rather, they have been given us because God loves us unconditionally.
Can we not, like the shepherds that night, start the habit to tell others about the generosity of God that we have experienced?