How Was the Ark of the Covenant So Powerful? #231

Everybody knows that the Ark of the Covenant is super-powerful and invincible, right? It actually melted Nazis in the Raiders of the Lost Ark! It caused the walls of Jericho to fall down! It killed Uzzah when he touched it! It even blessed the household of a Philistine when King David left it there and fled back to his palace. Since the Ark of the Covenant was so powerful, and seemingly undefeatable, how did the Israelites get destroyed by the Philistines in battle, and have the Ark taken? What could have happened??