There is more to salt than meets the taste buds. Salt has been used in many cultures as a valuable commodity. The word salary comes from an ancient word meaning “salt-money,” referring to a Roman soldier’s allowance for the purchase of salt. Someone who earns his pay is still said to be “worth his salt.” Salt has also been used to express promises and friendship between people. It was even considered by the Greeks to be divine. Today in many Arab cultures, if two men partake of salt together they are sworn to protect one another—even if they had previously been enemies. In some cultures, people throw salt over their shoulders when they make a promise. Who knew sodium chloride was so important?
In the ancient world, ingesting salt was a way to make an agreement legally binding. If two parties entered into an agreement, they would eat salt together in the presence of witnesses, and that act would bind their contract. King Abijah’s speech in 2 Chronicles 13:5 mentions just such a salt covenant: “Don’t you know that the LORD, the God of Israel, has given the kingship of Israel to David and his descendants forever by a covenant of salt?” Here, Abijah refers to the strong, legally binding promise of God to give Israel to David and his sons forever.
The Old Testament Law commands the use of salt in all grain offerings and makes clear that the “salt of the covenant” should not be missing from the grain offerings (Leviticus 2:13). Since the Levitical priests did not have land of their own, God promised to provide for them via the sacrifices of the people, and He called this promise of provision a “salt covenant” (Numbers 18:19). Salt has always been known for its preservative properties, and it is also possible that God instructed the use of salt so that the meat would last longer and taste better—and thus be of more value to the priests who depended upon it for their daily food.
The idea of a salt covenant carries a great deal of meaning because of the value of salt. Today, salt is easy to come by in our culture, and we don’t necessarily need it as a preservative because of refrigeration. But to the people of Jesus’ day, salt was an important and precious commodity. So, when Jesus told His disciples that they were “the salt of the earth,” He meant that believers have value in this world and are to have a preserving influence (Matthew 5:13).
The salt covenant is never explicitly defined in the Bible, but we can infer from the understanding of salt’s value and the contexts in which a salt covenant is mentioned that it has much to do with the keeping of promises and with God’s good will toward man.