Just to point out that salt isn't just a christian thing. In Japan, you sprinkle it to get rid of demons, to cast out bad spirits (and bad luck). t's sprinkled on the ground before sumo matches, and you often see references to it in pop culture (people pouring salt on someone to tell them to get out, saying "Hey, better pour some salt when they leave!" and so on in anime and manga). It seems to be fairly common, mythologically, that salt is anathema to bad spirits.