The lesson we learn from Christmas is love. Christ's love that was manifest in His coming, in His life, and in His death-is a love that sacrificed. In the Advent of Jesus Christ, we see a love that sought, not its own needs, but the needs of others. We see a love that considered, not what it would lose, but what others would gain. We see a love that so emptied self that others would be filled; a love that so humbled self that others would be lifted up.
The Christ of Christmas gave to the very end, ultimately forfeiting His own life, so that sinners would find salvation. That's what happened when God became a Man-and that's what Christmas is all about.