Here is a bit of Luther on Jacobs ladder where he speaks at some length on the theology of the cross. In this part, he points out that the angels act as if God is not in heaven but adore Christ in the depths and down in the dregs of human suffering. The angels, the highest creatures, adore and submit to the lowest one for there is God.
This then is the ascent adn descent of the angels of God and of the blessed who look on this, pay attention to it and proclaim it, as can be seen on the day of the nativity. They descend as though there were no God up in heaven. They come to Bethlehem and say: "Behold, I announce great joy to you. The Lord has been born for you ... They adore him as he now lies in the manger at his mothers breasts. Indeed they adore him on the cross, when he descends into hell, when he has been subjected to sin and hell, when he bears all the sins of the whole world. And they submit themselves forever to this lowest one.
Luther, Commentary on Genesis, Vol. 5 220.