I love the connection between Christmas & Missions. The whole idea of God coming to earth to redeem man is missional. "And the Word became flesh and dwelt among us!" (John 1:14).
This was posted on Desiring God's website recently:
"For its own soul the church [and me too] needs to be involved in missions. We will not know God in his full majesty until we know him moving triumphantly among the nations. We will not admire and praise him as we ought until we see him gathering a company of worshipers for himself from every people group on earth—including all the Muslim and Hindu and Buddhist peoples. Nothing enlarges our vision of God's triumphant grace like the scope of his saving work in history." (Piper, Don't Waste Your Life, pg. 172-3)