I was going to mention King Christian, too.  From what I have read in recent years, it would seem that the story that he appeared on the streets of Denmark wearing the Star of David may be apocryphal.  Still, I think the story is apt. Many years ago, I heard this story recounted in a Christmas homily.  The homilist suggested that what King Christian had done in willingly taking on the Star of David, uniting himself to the Jewish citizens of his kingdom, was precisely an act inspired by the Incarnation of the Son of God, who willingly took on our humanity. It was a memorable homily -- I'm recounting it from the distance of more than thirty years; and no one suggested that King Christian's act of solidarity was anything less than radically, profoundly Christian.
So, too, any act of solidarity we Christian might devise or perform to resist a Muslim registry.
I think that there will also be Jews who will likewise resist this evil.