Christian farmers didn't know much about the occult. To them, the hex sign was good luck. It was thought to ward off the "evil eye," which is a term that embraces all forms of envious malevolence, both intentional and accidental. The hex signs have the same function as nailing a horseshoe over your front door. Good luck, and warding off bad luck. The hex sign takes various forms, the pentacle being only one of them. Most of the farmers who used, or use, them don't really believe in magic. It is a superstition, similar to carrying a rabbit's foot on your keyring.