Once upon a time the devil attended Mass in a church where it was customary in either the Lord’s Prayer or in the Creed to sing: Et homo factus est, that is, “God’s Son has become a human being.” While they were singing this, the people just remained standing and did not kneel down. The devil was so incensed, that he slammed his fist into one man’s mouth, saying, You boorish bum, aren’t you ashamed to just stand there like a post and refuse to kneel for joy? If God had become OUR brother, as he did become YOUR brother, our joy would be so great that we wouldn’t know what to do with ourselves.
– Martin Luther, Fourth House Postil for Holy Christmas Day
There is a similar illustration in Luther’s sermons on John chapters 1-4 (AE Vol. 22).
The following tale is told about a coarse and brutal lout. While the words “and was made man” were sung in church, he remained standing, neither genuflecting nor removing his hat. He showed no reverence, but just stood there like a clod. All the others dropped to their knees when the Nicene Creed was prayed and chanted devoutly. Then the devil stepped up to him and hit him so hard it made his head spin. He cursed him gruesomely and said: “May hell consume you, you boorish ass! If God had become an angel like me and the congregation sang: ‘God was made an angel,’ I would bend not only my knees but my whole body to the ground!”