§ 6. The Sermon on the Mount (According to Matthew)

Under the Law of Moses, every offering of grain was to be free of leaven, or yeast. Salt not only enhances flavor but also kills yeast. The grain offerings discussed in Leviticus 2 were to be burned on the altar.

Leviticus 2:11, 13

No grain offering that you bring to the LORD shall be made with leaven, for you shall burn no leaven…as a food offering to the LORD.
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.

In the directions for the grain offerings of Leviticus 2 above, God referred to "the salt of the covenant with your God." God also calls it "a covenent of salt" in the instructions to Aaron about tithes in Numbers 18. The idea of a covenant invites us to see the salt as God's promise to preserve the Levites alive (who must go without lands and fields to provide for themselves).

Numbers 18:8, 19

Then the LORD spoke to Aaron, "Behold, I have given you charge of the contributions made to me, all the consecrated things of the people of Israel. I have given them to you as a portion and to your sons as a perpetual due….
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."

Something of the preserving power of salt can be seen in the episode of Elisha cleansing the waters of a certain city.

2 Kings 2:19–22

Now the men of the city said to Elisha, "Behold, the situation of this city is pleasant, as my lord sees, but the water is bad, and the land is unfruitful." He said, "Bring me a new bowl, and put salt in it." So they brought it to him. Then he went to the spring of water and threw salt in it and said, "Thus says the LORD, I have healed this water; from now on neither death nor miscarriage shall come from it." So the water has been healed to this day, according to the word that Elisha spoke.

Elisha adds a small amount of salt to the spring to make its waters drinkable. It's clear the salt cannot possibly cleanse a spring, whose source is underground, but rather that the Lord has done this. We can be confident that God will do the same today when we "have salt in ourselves."

Speaking with people who are not yet Christians requires us to think about the Lord's interests. We need enough salt to remove leaven, enough to enhance flavor, but not so much that the waters become undrinkable. Be truthful about the faith in Christ without returning evil for evil.

Colossians 4:5–6

Walk in wisdom toward outsiders, making the best use of the time. Let your speech always be gracious, seasoned with salt, so that you may know how you ought to answer each person.

There is nothing like salt, no substitute for its flavor. In the same way, there is nothing like the faith of a Christian.

The hope for an unbeliever is that he simply has yet to discover the truth; when he finds it, he may obey it. But when a Christian decides to leaves the Lord, what can be said that has not already been said?

2 Peter 2:20

If, after they have escaped the defilements of the world through the knowledge of our Lord and Savior Jesus Christ, they are again entangled in them and overcome, the last state has become worse for them than the first.

All the Levitical offerings requiring salt were burnt offerings. The aim is purity, a concept captured in this passage from Zechariah:

Zechariah 13:8–9

In the whole land, declares the LORD,
two thirds shall be cut off and perish,
and one third shall be left alive.
And I will put this third into the fire,
and refine them as one refines silver,
and test them as gold is tested.
They will call upon my name,
and I will answer them.
I will say, 'They are my people';
and they will say, 'The LORD is my God.'"

The church at Corinth had many concerns to address in the faith, and Paul encouraged them to do so before he would arrive for a third time. Part of addressing these concerns was to speak truth with one another in the pursuit of restoration, agreeing with one another (as he had called for in 1 Corinthians 1:10), and inviting the God of peace by living in peace.

2 Corinthians 13:9–11

…Your restoration is what we pray for. For this reason I write these things while I am away from you, that when I come I may not have to be severe in my use of the authority that the Lord has given me for building up and not for tearing down. Finally, brothers, rejoice. Aim for restoration, comfort one another, agree with one another, live in peace; and the God of love and peace will be with you.

While the language Jesus uses may sound harsh, salt that has already absorbed odors or liquids has been used up beyond any remedy. Hebrews echoes the dire warning:

Hebrews 6:4–8

It is impossible, in the case of those who have once been enlightened, who have tasted the heavenly gift, and have shared in the Holy Spirit, and have tasted the goodness of the word of God and the powers of the age to come, and then have fallen away, to restore them again to repentance, since they are crucifying once again the Son of God to their own harm and holding him up to contempt.
For land that has drunk the rain that often falls on it, and produces a crop useful to those for whose sake it is cultivated, receives a blessing from God. But if it bears thorns and thistles, it is worthless and near to being cursed, and its end is to be burned.