I recommend JB Weld. It sticks anything to anything, with the right surface prep. You will need a sharp steel knife, like a razor blade or exacto knife, to safely and carefully scratch a few rough areas on the backside of your metal. Do the same on the Bible inside the area you expect to stick the metal to. Let it dry for a few hours, as leather has trapped moisture inside the tanned area. Mix the epoxy, apply the metal to the Bible, and let dry. I recommend taping off the area around the metal just like masking tape to pull wet epoxy from where you do not want it to be. Be slow, precise, and patient, you only have one shot at this.