Salt is mentioned in the Bible several other times, and some of those times are in the Old Testament referring to the Covenant of Salt. Did you know there was a covenant of salt? It isn't really explained, just mentioned. Here are the two times the covenant is spoken of in the Old Testament-
You shall season all your grain offerings with salt. You shall not let the salt of the covenant with your God be missing from your grain offering; with all your offerings you shall offer salt. (Leviticus 2:13).
All the holy contributions that the people of Israel present to the LORD I give to you, and to your sons and daughters with you, as a perpetual due. It is a covenant of salt forever before the LORD for you and for your offspring with you.(Numbers 18:19)
Another interesting OT mention is that God gave the kingdom to David through a covenant of salt.
Ought you not to know that the LORD God of Israel gave the kingship over Israel forever to David and his sons by a covenant of salt? (2 Chronicles 13:5).
Salt will even again be required as part of the offerings in the Millennial Temple of Ezekiel. (Ezekiel 43:24).
Because salt is so stable, salt indicates perpetuity. Salt preserves. Salt cures the thing upon which it is thrown. Due to its unalterable nature, salt is the opposite of leaven (yeast). Here is my main point for part 2: Salt is an Old Testament picture looking toward God's New Testament promise.
Clarke Commentary On Leviticus 2:13-
It was called the salt of the covenant of God, because as salt is incorruptible, so was the covenant made with Abram, Isaac, Jacob, and the patriarchs, relative to the redemption of the world by the incarnation and death of Jesus Christ. ... So essentially necessary is salt that without it human life cannot be preserved.
Without salt, the world putrefies. Jamieson, Fausset, Brown Commentary says,
The remedy for this, says our Lord here, is the active presence of His disciples among their fellows. The character and principles of Christians, brought into close contact with it, are designed to arrest the festering corruption of humanity and season its insipidity.
But how, it may be asked, are Christians to do this office for their fellow men, if their righteousness only exasperate them, and recoil, in every form of persecution, upon themselves? The answer is: That is but the first and partial effect of their Christianity upon the world: though the great proportion would dislike and reject the truth, a small but noble band would receive and hold it fast; and in the struggle that would ensue, one and another even of the opposing party would come over to His ranks, and at length the Gospel would carry all before it.
Turning to the New Testament, Commenter Matthew Henry says of the salt covenant in relation to the NT verse of Christians being the salt of the earth,
Ye are the salt of the earth. This would encourage and support them under their sufferings, that, though they should be treated with contempt, yet they should really be blessings to the world, and the more so for their suffering thus. The prophets, who went before them, were the salt of the land of Canaan; but the apostles were the salt of the whole earth, for they must go into all the world to preach the gospel. It was a discouragement to them that they were so few and so weak.
What could they do in so large a province as the whole earth? Nothing, if they were to work by force of arms and dint of sword; but, being to work silent as salt, one handful of that salt would diffuse its savour far and wide; would go a great way, and work insensibly and irresistibly as leaven, ch. 13:33. The doctrine of the gospel is as salt; it is penetrating, quick, and powerful (Heb. 4:12); it reaches the heart (Acts 2:37). It is cleansing, it is relishing, and preserves from putrefaction.
Now Christ’s disciples having themselves learned the doctrine of the gospel, and being employed to teach it to others, were as salt. Note, Christians, and especially ministers, are the salt of the earth.
Old Testament pictures are New Testament promises. The two are related. When God had Moses lift up the brazen snake on the pole in the OT, it was a picture of the lifting up of the Son of Man on the cross. When we see water gushing from the rock, the Rock is Christ (1 Corinthians 10:1-4) and He is the water of Life. The Israelites ate bread in the wilderness, Jesus is the Bread of Life. You see what I mean when I say OT pictures point forward to NT promises. This pastor said recently,
God is showing you through past events, predictions of the future. What God did with His people in the past, becomes a pattern of what He’s going to do with His people in the future. God’s past faithfulness to His people becomes prophetic prediction of what God will later do with/for His people. (Mark McAndrew, How Does Sin Relate to God's Sovereign Plan?)My personal interpretation of the covenant of salt is that it points forward to the everlasting salting of the earth with God's people for His glory.
Salting cod as I showed in part 1 was an important historical method to preserve food for future use. Salt was the main agent used the world over to agent to slow the decay of meat and other foods so that they could be preserved for a longer period. By now of course you see the relation of the OT Covenant of Salt and the NT believers being salt of the earth. Salt is a powerful metaphor of what God has done and is doing. In the New Testament, the references to us Christians being salt of the earth refer to those Christians who obey God and do his will, can act as a preservative of the human race by slowing down the moral and spiritual decay of the world.
One way we do this is through our speech:
Let your speech always be gracious, seasoned with salt, so that you may know how you ought to answer each person. (Colossians 4:6)
Salt is good, but if the salt has lost its saltiness, how will you make it salty again? Have salt in yourselves, and be at peace with one another. (Mark 9:50).
We lose our saltiness when we deny the Spirit, refuse to repent, sin, backslide, stay out of the word, etc. The more Godly character is in us, the more we can act as a preservative in the world. Aren't you glad there were Godly characters around you before you were saved, and thus you were preserved from moral and spiritual decay? The LORD used salt to purify the waters when he had Elisha the Prophet throw salt into the spring. (2 Kings 2:21). The salt didn't actually heal the waters. It was a symbolic act, just as we believers are salt and God sprinkles us among the people as His healing, preserving agent against the corruption and decay of the world.
We're salt. Go out and preserve as many as possible.