Though this passage isn’t a traditional “Christmas” message (you won’t find it on many cards), I think it captures the essential Christmas message better than most because it includes both the nature and ultimate purpose of the incarnation:
“Have this mind among yourselves, which is yours in Christ Jesus, who, though he was in the form of God, did not count equality with God a thing to be grasped, but made himself nothing, taking the form of a servant, being born in the likeness of men. And being found in human form, he humbled himself by becoming obedient to the point of death, even death on a cross. Therefore God has highly exalted him and bestowed on him the name that is above every name, so that at the name of Jesus every knee should bow, in heaven and on earth and under the earth, and every tongue confess that Jesus Christ is Lord, to the glory of God the Father.” Phil. 2:5-11.
In the incarnation, Jesus made a staggering condescension by setting aside some of his divine attributes and becoming a man (who, by nature, is a servant). And he did so for the purpose of being obedient to death on a cross so that God ultimately would receive all the glory. Now that message can make for a very merry Christmas!