A tricky situation where law and religion collide. The parents might say, "Of course the amulets wouldn't protect the children from acid, anyone would know that". But if many people believe that amulets do have magical powers, and that making merit at the temple means they will receive rewards now or in the next life, was the monk so crazy, in this context, to believe that the amulets would protect them? Or do the parents think that that amulet failed on this occasion, so they need compensation, without it really challenging their faith at all?