Three times in his teaching Jesus refers to salt, and always in a figurative sense. The first is in the Sermon on the Mount, and follows immediately after the Beatitudes. Jesus had declared who are “blessed”; and all the Beatitudes until the last one were expressed objectively: “Blessed are the poor”; but in the last, while he began “Blessed are they” he at once applied it to the disciples: “Blessed are ye, when men shall reproach you”. This transition to the direct address leads on to saying: “Ye are the salt of the earth: but if the salt have lost its savour, wherewith shall it be salted? It is thenceforth good for nothing but to be cast out, and to be trodden under foot of men” (Matthew 5:13). The “blessed”, his disciples, are the “salt of the earth”.
Salt preserves and gives flavour to food. The fishermen among Christ’s hearers knew how quickly their harvest of the sea corrupted unless taken to the pickling vats of Bethsaida. All his listeners knew that in the warm atmosphere of their land any dead thing quickly became tainted and perished. In what way, then, were the “blessed” like unto salt? The general view, the easy interpretation, is that the disciples of Jesus are the preserving element in society, preventing by their influence the spread of corruption. Some go so far as to say that as Sodom would have been saved for ten righteous men’s sake, so the world is not destroyed because of the “Christians” in it. There is an element of truth in these ideas: for “the elect’s sake” God does direct the world for the development of His purpose; and the moral principles of Christ’s teaching have in measure affected for good some things in “society”; but it remains that the “world” will be destroyed, and that because of the unchecked corruption in it.
Salt has savour
It would seem to be rather of the “savour” that Jesus is thinking, for he at once speaks of this being lost, while no mention is made of the preserving power: and men are “salt” as they have the savour of salt — men as they are in themselves and not as they influence their fellows. This is borne out when we remember that Jesus uses two figures in one breath: his disciples are “salt” and they are “the light of the world”; the one saying describes their own quality and the second their relationship to those about. His disciples then, who show meekness, mercy, purity of heart, desire for righteousness, have the wholesomeness and the “savour” that God desires. They can lose this quality, as salt in Palestine does lose its saltness and is then fit for no useful purpose. Thomson, in The Land and the Book, tells of an importer trying to cheat, losing money by his salt losing its saltness.
Everyone salted with fire
Mark’s reference brings in another association of salt with other ideas involved which Jesus must have had in mind in all his allusions to salt. Passing through Galilee, he foretold his death and resurrection; but the apostles had other preoccupations which prevented them following his thought when he spoke of suffering and death; they were discussing which one of them should be the greater in the kingdom he was to establish. Their minds were so fixed on an immediate restoration of this kingdom that they could not think of Jesus dying. They were so concerned with their own pre-eminence that they had no sympathy for the leader whose mind was fixed on effacement of self, and suffering and sacrifice. Jesus proceeded to teach them that the way to exaltation was by the abasement of self: “If any man desire to be first, the same shall be last of all, and servant of all”. Jesus took a child, and pointed out the need for childlikeness of disposition; he then said that it was better that a disciple should now sacrifice hand or foot or eye, if it be necessary, than by keeping them be cast at last into Gehenna and be completely destroyed. Then he gave the reason for this counsel: “For every one shall be salted with fire, and every sacrifice shall be salted with salt. Salt is good: but if the salt have lost his saltness, wherewith shall ye season it? Have salt in yourselves, and have peace one with another” (Mark 9:49-50).
The salt of the offering
Here again, the context is the guide. Jesus had put before them the amputation of desire now, or complete destruction — “where their fire is not quenched” — in the future. To escape the latter everyone must now be “salted with fire”; and the verb “salted” recurs: “every sacrifice shall be salted with salt”; and this second occurrence explains the first. It refers us to the Law of the Offerings. While leaven and honey were forbidden adjuncts of the meal offering, both being agents of fermentation, salt was essential: “Every oblation of thy meat offering shalt thou season with salt: neither shalt thou suffer the salt of the covenant of thy God to be lacking from thy meat offering: with all thine offerings thou shalt offer salt” (Leviticus 2:13).
The salt of the covenant
The salt with the meal offerings was a token of covenant relationship. To partake of a meal together was a “covenant of salt” between men. It was a covenant ratified by a meal. So rigid was this rule that the story is told of a thief who partook of food in a tent, and when caught escaped punishment because the sheik regarded the act of partaking food, even under those circumstances, as a “covenant of salt”. The salt with the offering spoke of the covenant by virtue of which the meal offerings was acceptable. Remembering this, and that Leviticus 2:13 is the source of the phrase used by Jesus, his meaning must be that as every offering must be made in the bonds of the covenant (salted with salt) so the cutting off of the desires of sin were essential as a condition of offering (salted with fire). Fire is purifying; to be salted with fire is to be purified even as the covenant requires, removing stumbling blocks even at the cost of limbs.
Salt and peace
Jesus make the personal application to the situation before him, when contentious men in self-esteem were seeking precedence over each other. He also uses the phrase on other occasions about salt losing its saltness. Thy were “salt” as he had before told them: and in this context the greater fullness of his thought is seen. They had the savour and wholesomeness as being in God’s covenant. They could lose their “saltness” by unworthy thought and rivalry: were, in fact, in danger of doing so then. In sharing the covenant sacrifice which he was making in subduing his will to the Father’s will, they would resolve their disputes. When self is placed on the altar contentions regarding precedence do not arise. “Have salt in yourselves, and have peace one with another”, he therefore counsels. In other words, “Keep in yourselves covenant principles, as God’s people; make the needful sacrifice of self; and your contentions will pass and you will have peace among yourselves”.
Speech seasoned with salt
Paul has an echo of these sayings in Colossians 4:6: “Let your speech be always with grace, seasoned with salt, that ye may know how ye ought to answer every man”. The parallel in Ephesians 4:29 is instructive, and reads: “Let no corrupt communication proceed out of your mouth, but that which is good to the use of edifying, that it may minister grace to the hearers”.
A corrupt, or putrid word, is unwholesome and unfitted for the mouths of saints. It is not good, does not build up, nor minister grace. Speech seasoned with salt is clean, of good tang, of the quality that belongs to God’s covenant — which Paul expressed in characteristic fashion as “with grace” and “ministering grace”, using a word which allows the play of graciousness with the deeper meaning of the relationship between God and man made possible by God’s favour. Speech seasoned with salt is such as may be heard by God acceptably, speech free from the foul and the suggestive, which are so often conspicuous in the talk of men.
Salt without savour is good for nothing
The saying in Luke’s record forms part of an address to the multitudes crowding around Jesus, in which he warns them of the demands of discipleship. There came a time when men had to decide about him they could not follow light heartedly out of curiousity or to see the sensational cures or to share in his provision for their need. Three times he uses the words “cannot be my disciple”. The man who puts first home ties and the affections of the present, and even his own life; the man unprepared to crucify his “self”; the man who cannot finish the task begun, renouncing all that he hath — none of these can be his disciples. “Salt therefore is good”, he continues, but “if even the salt have lost it savour, wherewith shall it be seasoned?” To follow him was to take on the tang of salt that made them acceptable. But the “savour” must be retained, or it became unprofitable. So, too, would they if they did not count the cost and in patient continuance endure to the end.
“Wherewith shall it be salted?” The emphasis is on the “it”. Degenerate salt cannot be “salted”, and how can people who have taken on the quality of salt, losing it, be acceptable? Neither is of use, as Jesus emphasizes. Salt in limited quantities was good for the land; it was mixed with the manure-heap, but “saltless” salt could serve no purpose at all. Men threw it away.
— John Carter (Parables of the Messiah)