They were slaughtered trying to stop real-life raiders of the lost ark — an artifact so powerful and holy they were forbidden from ever seeing it. The harrowing mass-murder of at least 800 people at an Ethiopian church in Tigray highlighted the apparent whereabouts of the Ark of the Covenant, one of the biggest mysteries in religion and the stuff of movie legend. The ark — a large, gold-covered wooden chest said to hold Moses’ Ten Commandments — was held at the Temple of Solomon in Jerusalem for centuries, but vanished after Jerusalem was sacked in 586 or 587 BC,...