Christmas is not merely about Christ's birth, but that he was born FOR US.

"Fear not, for behold, I bring you good news of great joy that will be for all the people. For unto you is born this day in the city of David a Savior, who is Christ the Lord." ~ Luke 2.10-11

In a sermon on Christmas Day, 1540, Martin Luther preached on this text, explaining how the gospel is not merely news about Christ's birth, but news about Christ's birth for us. Christmas is not a celebration of our Lord's birth, but good news that One promised by God to live, die, and rise again for our sakes had arrived into the world....

"With these words the angel demonstrates the gospel most clearly...He takes on himself the office and words that conform to the gospel and says, evangelizo. He does not say, 'I preach to you,' but rather, 'I speak gospel to you; I am an evangelist; my word is gospel.' Thus the word gospel means a good, joyful message which is the proclamation of the new covenant. What does the gospel say? Listen. He says, 'I bring you good news of great joy; my gospel speaks of great joy.' Where is it? Listen again. 'To you is born a Savior, Christ the Lord, today in Bethlehem in the city of David.' See here what the gospel is, namely, a joyful sermon about Christ our Savior. Whoever preaches him rightly preaches the gospel and pure joy. How can a heart hear of greater joy than that Christ is given to him as his own? He not only says that Christ is born, but he also makes his birth our own by saying 'your Savior.' Therefore, the gospel not only teaches the history and events of Christ but also makes him our own and gives him to all who believe it, which is the true and proper nature of the gospel. What would it help me if Christ had been born a thousand times and it were sung daily in a most lovely manner, if I were never to hear that he was born for me and was to be my very own?"