Theodosius Harnack, Luther scholar of note, said that for Luther the imperative was to have "God deep in the flesh." Christmas celebrates just that: God deep in the flesh. So great was God's longing for his creatures' redemption, says Luther, that God's preference for human nature over angelic nature might even have provoked the angels to jealousy!

But (Psalms 8) nudges that issue: what are human beings that you are mindful of them? They have been made a bit lower than angels but crowned with glory and honor. A preference for humans: in that lies the Christmas gospel. ...

There is God in the flesh, thriving in a placenta, protected by a water bag, bouncing on a donkey ride to Bethlehem where his folks had to meet the local IRS. No different than any other baby at the time. While God preferred human nature to the angelic, God asked no human favors and got none. When inns are full they are full. Sleep where one can. God deep in the flesh became God deep in the straw. Mary, the mother of the Creator, sustained the one who sustained all the living.