To possess a key is to possess the pivotal knowledge of some eternal principle that grants access to higher levels of spiritual ability and power. A very small key can open a very large door. But take away the key and the door may as well be a wall.
What a strange thing it would be to find a king that chose to set aside the usual tools of force and fear, to instead rule by patient persuasion and love. And yet this is exactly how God “rules” his people.