The babe in the manger is LORD.
The heart of Christmas is this realization: Something incredible, unique, dynamic, and world-changing happened when Jesus was born. The witness of the New Testament is that Jesus fulfilled the promise of God to come dwell with His people.The LORD, Yahweh, has come down. Advent reminds us that Jesus is Immanuel, God with us.
And He is for all of us. Zechariah's prophecy saw many nations joining themselves to the Lord. In the Revelation Jesus gave to John, he saw even more: People from every nation, tribe, and tongue. Every single people group on earth will be represented around the throne. No exceptions, no limitations. On that beautiful day around the throne, there will be no unreached people groups. None.
Jesus Himself linked His second advent, His second coming, to this truth: And this gospel of the kingdom will be proclaimed throughout the whole world as a testimony to all nations, and then the end will come. (Matthew 24:14 ESV) If we long for His return, as Scripture says we should, then we should long to be involved in the one thing that will be required to hasten His return -- reaching those "nations" (the word refers to people groups, what we might consider tribes or clans rather than political nations) -- those people groups who have never heard.
On the day Jesus was born in the manger, God send angels to herald the news to shepherds in the field. Today, He sends His people - the church - to herald the news to those who have never heard. What is that message? God Himself has made a way for relationship to Him. He has entered the world He created, taken on human flesh, so that He could bear the death penalty for the sins we committed against a holy God. Jesus, full of grace and truth, revealed God's heart of love and mercy toward mankind.
Hallelujah, what a message! Hallelujah, what a Savior!