Gelobet seist du, Jesu Christ,daß du Mensch geboren bistvon einer Jungfrau, das ist wahr,deß freuet sich der Engel Schar.Kyrieleis.Des ewgen Vaters einig Kindjetzt man in der Krippen findt,in unser armes Fleisch und Blutverkleidet sich das ewig Gut.Kyrieleis.Den aller Weltkreis nie beschloß,der liegt in Marien Schoß,er ist ein Kindlein worden klein,der alle Ding erhält allein.Kyrieleis.Das ewig Licht geht da herein,gibt der Welt ein neuen Schein,es leucht wohl mitten in der Nachtund uns des Lichtes Kinder macht.Kyrieleis.Der Sohn des Vaters, Gott von Art,ein Gast in der Welt hie wardund führt uns aus dem Jammerthal,er macht uns Erben in seim Sal.Kyrieleis.Er ist auf Erden kommen arm,daß er unser sich erbarmund in dem Himmel macht reichund seinen lieben Engeln gleich.Kyrieleis.Das hat er alles uns gethan,sein groß Lieb zu zeigen an,des freu sich alle Christenheitund dank ihm des in Ewigkeit.Kyrieleis.V. 1 aus dem 15. Jahrhundert,V. 2-7 Dr. M. Luther, 1524.
My prose translation:
May You be praised, Jesus ChristThat You are born manOf a virgin, that is true,Therefore the angel host rejoices.Kyrie eleison.The only child of the eternal FatherNow one finds in the mangerIn our poor flesh and bloodThe eternal good clothes Himself.Kyrie eleison.He Who never ends the whole orbit of the worldLays in Mary's lap,He is become a little childWho alone maintains all things.Kyrie eleison.The eternal light goes in there,Gives to the world a new appearance,It shines well in the middle of the nightAnd makes us children of the light.Kyrie eleison.The Son of the Father, God by natureBecame a guest here in the worldAnd led us out of the vale of tearsHe makes us heirs in His hall.Kyrie eleison.He is come on the earth poorTo have pity on usAnd make us rich in HeavenAnd like His dear angels.Kyrie eleison.All this He has done for usTo display His great loveTherefore rejoice, all ChristendomAnd thank Him in eternity.Kyrie eleison.Verse 1 from the 15th centuryVerses 2-7 Dr. Martin Luther, 1524.
"Schein" has two different meanings (glow, light, shine or appearance, look), and either could work in the context ("gibt der Welt ein neuen Schein"). I went with appearance.
"Und uns des Lichtes Kinder macht" (and makes us children of the light) may be a reference to part of Ephesians 5:8: "Walk as children of light."
I couldn't decipher the meaning of the second "des" in the last verse (the first seems to be an abbreviation of "deshalb"), but I don't think leaving it out affects the meaning too much.
This hymn appears as "All Praise to Thee, Eternal God" in The Lutheran Hymnal (#80), "We Praise, O Christ, Your Holy Name" in Lutheran Worship (#35), and "We Praise You, Jesus, at Your Birth" in The Lutheran Service Book (#382). The TLH and LW versions are abbreviated, but the LSB version has all seven verses. In all three hymnals and as the Gesangbuch notes, the text is sung to "its own melody." Here's the TLH arrangement: