Most people rarely go to mass on the morning of the 24th, but the readings are an interesting choice. The gospel is the Canticle of Zachariah, but the first reading goes back to a single moment in the life of David.
Rather than thinking of God when things are going wrong in his life. David is in the best place he has been in a while. In a moment of wisdom David recognizes that what has been accomplished was not all his own doing but was accomplished with the health of God. He then looks at how he is living and realizes that God has no dwelling place. David then makes THE promise, to build a dwelling place for God.
It is then that God makes the promise to David that it will be a descendent from his line who will the king. Even David could never have imagined how God's promise would be fulfilled.
As the sun goes down today, churches around the world will begin our celebration of Christmas. To prepare ourselves, perhaps it is time for us to imitate David, to look at our lives and see all the blessings we have received from God.