Luke 2:1-20: "1 In those days a decree went out from Caesar Augustus that all the world should be registered. 2 This was the first registration when Quirinius was governor of Syria. 3 And all went to be registered, each to his own town. 4 And Joseph also went up from Galilee, from the town of Nazareth, to Judea, to the city of David, which is called Bethlehem, because he was of the house and lineage of David, 5 to be registered with Mary, his betrothed, who was with child. 6 And while they were there, the time came for her to give birth. 7 And she gave birth to her firstborn son and wrapped him in swaddling cloths and laid him in a manger, because there was no place for them in the inn.
"8 And in the same region there were shepherds out in the field, keeping watch over their flock by night. 9 And an angel of the Lord appeared to them, and the glory of the Lord shone around them, and they were filled with fear. 10 And the angel said to them, 'Fear not, for behold, I bring you good news of great joy that will be for all the people. 11 For unto you is born this day in the city of David a Savior, who is Christ the Lord. 12 And this will be a sign for you: you will find a baby wrapped in swaddling cloths and lying in a manger.' 13 And suddenly there was with the angels a multitude of the heavenly host praising God and saying, 14 'Glory to God in the highest, and on earth peace among those with whom he is pleased!'
"15 When the angels went away from them into heaven, the shepherds said to one another, 'Let us go over to Bethlehem and see this thing that has happened, which the Lord has made known to us.' 16 And they went with haste and found Mary and Joseph, and the baby lying in a manger. 17 And when they saw it, they made known the saying that had been told them concerning this child. 18 And all who heard it wondered at what the shepherds told them. 19 But Mary treasured up all these things, pondering them in her heart. 20 And the shepherds returned, glorifying and praising God for all they had heard and seen, as it had been told them."
2 Corinthians 8:9: "For you know the grace of our Lord Jesus Christ, that though he was rich, yet for your sake he became poor, so that you by his poverty might become rich."
John 1:1-5: "1 In the beginning was the Word, and the Word was with God, and the Word was God. 2 He was in the beginning with God. 3 All things were made through him, and without him was not any thing made that was made. 4 In him was life, and the life was the light of men. 5 The light shines in the darkness, and the darkness has not overcome it."
John 1:10-14: "10 He was in the world, and the world was made through him, yet the world did not know him. 11 He came to his own, and his own people did not receive him. 12 But to all who did receive him, who believed in his name, he gave the right to become children of God, 13 who were born, not of blood nor of the will of the flesh nor of the will of man, but of God.
"14 And the Word became flesh and dwelt among us, and we have seen his glory, glory as of the only Son from the Father, full of grace and truth."
Philippians 2:5-7: "5 Have this mind among yourselves, which is yours in Christ Jesus, 6 who, though he was in the form of God, did not count equality with God a thing to be grasped, 7 but made himself nothing, taking the form of a servant, being born in the likeness of men."
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The Luke text is the source for the first two verses, more so the second (which mentions the "infant small... in a manger") than the first (which is more general).
The two selections from John 1 form the third verse, which explains how Jesus "hides / His all-creating light" in "an earthborn form."
The verse from 2 Corinthians 8 informs the fourth verse, which also talks about "a great exchange." The hymn seems to expand on 2 Corinthians' "so that you by his poverty might become rich" by specifically describing that "in return [He] gives us His realm, His glory, and His name."
The fifth verse starts with the line "He is a servant, I a lord," which - while still drawing on 2 Corinthians 8:9 - also uses Philippians 2:7, specifically "taking the form of a servant."
The two selections from John 1 form the third verse, which explains how Jesus "hides / His all-creating light" in "an earthborn form."
The verse from 2 Corinthians 8 informs the fourth verse, which also talks about "a great exchange." The hymn seems to expand on 2 Corinthians' "so that you by his poverty might become rich" by specifically describing that "in return [He] gives us His realm, His glory, and His name."
The fifth verse starts with the line "He is a servant, I a lord," which - while still drawing on 2 Corinthians 8:9 - also uses Philippians 2:7, specifically "taking the form of a servant."
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There are a number of uncited Biblical sources in the sixth verse. The first line is "He is the key and He the door," which uses two names for Jesus: the Key of David (Isaiah 22:22) and the Door (John 10:9). The third line ("The angel bars the way no more") refers to the angel sent to guard the way to the tree of life in the garden of Eden (Genesis 3:24).