Unto Us a Child Will Be Born takes the longing of Come, Thou Long-Expected Jesus and infuses it with a sort of sort of celebratory expression of expectation. If you listen closely, you will see that the melody in the Savior Foretold Underscore is really just an augmented (that’s a fancy music work for elongated) version of the melody. Every time the choir sings the refrain “Unto us a Son will be given… Unto us a Child will be born”, you are hearing a quicker version of the melody that underscored the reading of Isaiah 9:6-7.
You may also recognize this same melody when it reappears later on in the Child Is Born Underscore. This melodic theme makes use of a certain kind of modal harmony called Mixolydian. Now I’m not using this fancy word Mixolydian to “mix” you up. It’s important to note it’s unique sound because I use it to symbolize the regal, kingly role of Christ. Mixolydian sounds a lot like normal major key music, but it has a lowered seventh note in its melodic scale that gives the music this sort of regal quality. I think this interesting musical sound, along with the use of orchestral colors like the tambourine and low brass, help this piece paint a mental picture of what it might have been like to experience worship in Solomon’s temple. Unto Us a Child Will Be Born is essentially a celebration of God’s faithfulness in providing His promised Messiah to us in the person of Jesus Christ–Emmanuel–God with us.