Reflections of a stormy petrel

That is not the only point. To say that God had given certain men or institutions authority does not mean that He gave them absolute spiritual authority - after all, he had made Satan king over Hell, too, and that was a kingship just as valid and validated by God as any earthly one. (In later medieval magic, the devils are often called by titles of nobility and office that parallel those of earthly kings, so that Hell has not only a King, but dukes, chancellors and so on.) The difference is that monarchy by divine right effectively casts itself as the image of God on Earth, claiming the same authority on Earth as God has in Heaven. The highest of mediaeval lords would have been shocked by such claims.