It calls for the coming of our redeemer and judge but it is moreso meant to be used so that we are moved day after day through history -- heilsgeschichte -- a holy history of God's salvation of the world.
Check our Hymnal 1982, hymn # 56 and you'll see in the left-hand margin a succession of dates beginning on December 17 that take us to December 23. Each stanza re-calls God's saving acts that include Wisdom's accompaniment at creation to protect us from chaos, God's commandments on Sinai, the reign of David, and finally our being united in peace with our King.
December 17 - O come, O come, Immanuel,
and ransom captive Israel
that mourns in lonely exile here
until the Son of God appear.
refrain Rejoice! Rejoice! Immanuel
shall come to you, O Israel.
December 18 - O come, O Wisdom from on high,
who ordered all things mightily;
to us the path of knowledge show
and teach us in its ways to go. Refrain
December 19 - O come, O come, great Lord of might,
who to your tribes on Sinai's height
in ancient times did give the law
in cloud and majesty and awe. Refrain
December 20 - O come, O Branch of Jesse's stem,
unto your own and rescue them!
From depths of hell your people save,
and give them victory o'er the grave. Refrain
December 21 - O come, O Key of David, come
and open wide our heavenly home.
Make safe for us the heavenward road
and bar the way to death's abode. Refrain
December 22 - O come, O Bright and Morning Star,
and bring us comfort from afar!
Dispel the shadows of the night
and turn our darkness into light. Refrain
December 23 - -O come, O King of nations, bind
in one the hearts of all mankind.
Bid all our sad divisions cease
and be yourself our King of Peace. Refrain