March 25, 2017 – The Function of Salt

You are the salt of the earth; but if the salt has become tasteless, how can it be made salty again? It is no longer good for anything, except to be thrown out and trampled under foot by men.—Matt. 5:13

Salt has always been valuable in human society, often much more so than it is today. But the particular characteristics of salt that Jesus was referring to in this passage have resulted in various suggestions.

Some interpreters point out that salt is white and therefore represents purity. As the “pure in heart” (v. 8), Jesus’ disciples are to be pure before the world and are to be God’s means of helping purify the rest of the world.

Others emphasize the characteristic of flavor. Just as many foods are tasteless without salt, the world is drab and tasteless without the presence of Christians.

Because salt stings when placed on a wound, some interpreters believe Jesus meant to illustrate that Christians are to sting the world, prick its conscience, and thus make it uncomfortable in the presence of God’s gospel.

Salt also creates thirst. So others believe God intends for His people to live before the world in such a way that others will be made aware of their spiritual dehydration.

While all of these interpretations are reasonable, it’s likely Jesus was primarily referring to salt as a preservative. Christians are a preserving influence in the world; they retard moral and spiritual spoilage. As God’s children and as temples of His Holy Spirit, we represent God’s presence in the earth. We are the salt that prevents the entire earth from degenerating even faster than it already is.

In what ways are you and your church personifying the various properties of salt, whether by words, actions, or outreaches? Think very specifically. Which of these examples are proving to be the most effective at this, and why?[1]

Do You Make Men Thirsty?

Matthew 5:13

In Matthew 5:13 we come to a new section of the Sermon on the Mount. We pass from a basically abstract definition of the Christian to a functional one. Jesus said, “You are the salt of the earth. But if the salt loses its saltiness, how can it be made salty again? It is no longer good for anything, except to be thrown out and trampled by men.”

We all know the difference between an abstract definition of a thing and a functional definition, if we think about it. For instance, almost every dictionary definition of a word is abstract. We turn to the word “hunger” in Webster’s New Collegiate Dictionary and read, “an uneasy sensation, occasioned normally by the want of food.” However, we could also define hunger functionally. We could also say, “Hunger is the one and a half billion people in this world who live always on the verge of starvation and who die at the rate of 15,000 daily as the result of malnutrition.” The second definition is anything but abstract. And, of course, it is better. In the same way the dictionary tells us that “justice” is “the principle of rectitude and just dealings of men with each other.” But we could also say that justice is enacting good laws, caring for the poor, raising children properly, and many other things.

We have the same thing in the sphere of theology. The Westminster Shorter Catechism asks the question, “What is God?” And it answers, “God is a spirit, infinite, eternal, and unchangeable, in His being, wisdom, power, holiness, justice, goodness, and truth.” But it is also true, even more true, that God is Jesus Christ who died for our sin and who rose again for our justification.

The second definition in each of the cases I have mentioned gives us an understanding of the term in action; it produces the effect that Jesus produced by his further, functional definitions of the true Christian. “You are the salt of the earth.” “You are the light of the world.” By these definitions Jesus was saying that while it is true that the Christian is to be poor in spirit, mournful for sin, meek, thirsty for righteousness, merciful, pure in heart, and disposed to make peace, nevertheless he is never to be these things in isolation from a very real and sharply antithetical world. He is to manifest those characteristics in the world. And what is more, he is to practice these things in a way that will affect the world positively, as salt affects the medium to which one applies it.

A Decaying World

This is of great significance for our understanding of the nature of true Christianity, especially in our present day. Jesus was saying, “Those who are my disciples should affect the world positively by the way in which they live.” But as I view the world today, there is not nearly enough of this positive action for good in the world by Christians, even though many people are aware that something of this nature is precisely what the world needs.

At the end of the nineteenth century there was a feeling of confident optimism in the western world, based on the belief that an ongoing biological and philosophical evolution would eventually solve all man’s troubles and lead to something closely akin to the Greeks’ “Golden Age.” The idea was that all of human life was advancing and rising upward. Dr. D. Martyn Lloyd-Jones writes perceptively of this age, “It is indeed pathetic to read the prognostications of the thinkers (so-called), the philosophers and poets and leaders, towards the end of the last century. … Wars were going to be abolished, diseases were being cured, suffering was going to be not only ameliorated but finally eradicated. It was to be an amazing century. Most of the problems were going to be solved, for man had at last really begun to think. The masses, through education, would cease giving themselves to drink and immorality and vice. And as all the nations were thus educated to think and to hold conferences instead of rushing to war, the whole world was very soon going to be paradise. That is not caricaturing the situation; it was believed confidently.”

Today, however, there are not many people who think like that. Where there was once a confident optimism, there is now real pessimism and acute despair. Even the ones who are still confident in some areas express their more limited optimism guardedly. There is an awareness that something more than a theory of progress is necessary, that there must, in fact, be something akin to a new life embodied in a new breed of men. This is what the gospel of Jesus Christ offers. And yet, what do we find? Instead of the active, permeating, preserving, and transforming power of the gospel of Jesus Christ always operating in the world through all Christians, too many Christians are sitting on the sidelines without the “savor” provided by the Lord Jesus Christ and fit only—if we are to take Christ’s words literally—“to be cast out, and to be trodden under foot of men.”

I am well aware that there are good historical reasons why an evangelical church that once gave fuel and impetus to the greatest social movements the world has seen has come to be outdistanced by others and at times even to be hostile to the applications of the gospel to the contemporary world. Daniel O. Moberg, author of the book, Inasmuch, lists ten reasons in his historical study of the neglect of the social aspects of the faith by evangelicals: a preoccupation with valid theological battles, a misinterpretation of the prophecies that in the last days things on this earth will get worse to mean that they will never in any circumstances get better, a belief that social concerns are antithetical to a concern for the salvation aspects of the church’s message, a concern for personal piety, the idea that politics are intrinsically “dirty,” a growing conformity to the world’s standards in business and political life by Christians, and other things also. But the explanation does not excuse the situation in which we find ourselves today. Nor does the situation itself negate the moral imperatives of Christ’s teachings.

According to Jesus, the Christian is clearly to influence his society. And this must be true wherever the principles of the gospel impinge upon the religious, political, economic, or social issues of the Christian’s community.

Uses of Salt

All this falls into a much clearer focus when we consider the actual uses of salt, particularly those that were most valued in ancient times.

First, in Christ’s day and for many centuries thereafter (in fact, until nearly modern times), salt was the most common of all preservatives. There were no refrigerators in ancient times, no deep-freeze units. The Mediterranean world was largely tropical. In such a climate and in the face of such conditions, salt was used to keep things from going bad and becoming rotten, particularly meat. It was able to resist spoilage and keep putrefaction at bay. When Jesus said that those who followed him were the salt of the earth, therefore, he was teaching that the world apart from God is rotten because of sin, but that through his power his disciples were able and actually obliged to have a preserving and purifying effect upon it.

Do you see this clearly? If you do, the principles involved in this statement will keep you from the two opposing errors that have always gone along with programs to express the Christian’s social responsibility. The first error is the thought that the world is basically good and will gradually become better and even perfect through Christian social action. In opposition to this understanding, Christ says that the world is basically rotten. This means that even though it may appear healthy for a time, it is dead spiritually. It means that the life has gone out of the body and that the microbes of sin will eventually (if left to themselves) reduce it to a stinking, unapproachable carcass.

The other error is the view that because this is so, because the world is rotten, the Christian should try to disassociate himself from the world as much as possible, retreating to a monastery or to one of our white (or black), middle-class, self-protecting churches. And he should let the world go to hell. The answer to this error is that the Christian is to be a preserving force in the world wherever God has placed him. The salt never did any good when it was sitting on one shelf and the meat on another. To be effective, the salt had to be rubbed into the meat. In a similar way, Christians must allow God to rub them into the world. And this means that they must be Christians at work, Christians in politics, Christians at home, Christians everywhere else that a normal life in their own society would take them.

“Oh,” someone says, “that would mean that I would have to be taken out of the salt shaker and spread around, and I might get dirty and even seem to dissolve or disappear!” Yes, that is what it means. But God is the One who provides the flavor, and the flavor does not disappear when the salt is dispensed or dissolved.

In fact, there is even a sense in which the salt must dissolve if the flavor is to be released, and for this reason God sometimes shakes the salt shaker through persecutions so that the salt will fall out and let this happen. Sometimes it will mean that we shall have to dissolve to our own interests, that we shall have to extend ourselves in areas of the world where we do not see many Christians. We shall feel lonely and even depressed, but that is where the salt is active.

I should add a fact that is well known to the medical world. If a body does not give off salt through perspiration, what happens? It retains water, and it becomes bloated. In the same way, the church will become bloated and desperately unhealthy if the salt is not dispersed in this work of preservation.

Source of Flavor

There is a second thing that salt is good for, and that is to provide flavor. The Christian, through the life of Jesus Christ within and the verities of the gospel, is to lend flavor to a flavorless, insipid world. The pleasures of the world are unsatisfying without Jesus Christ. They fill for a time. But they are rather like a Chinese dinner, and the person is soon left empty again. Consequently, those who pursue them are doomed to a constant and relentless search for that which will never satisfy the true hunger and desire of their soul. Christians are to be present as those who know something different and whose satisfaction in Christ can be seen and known by their unbelieving contemporaries.

Unfortunately, it often has been the other way around. Non-Christians have looked at Christians and have said, “What an insipid bunch of people; I would never want to be like one of them.” The nineteenth century poet and critic A. C. Swinburne wrote of Jesus: “Thou hast conquered, O pale Galilean; the world has grown grey from thy breath.” Oliver Wendell Holmes once said, “I might have entered the ministry if certain clergymen I knew had not looked and acted so much like undertakers.” And the poet and author Robert Louis Stevenson once wrote in his diary, as if he were expressing an exceptional fact, “I have been to church today, and am not depressed.”

Those are honest remarks by people who have seen an insipid Christianity. And if they or their followers are to see something different, they must see it in the only place it can or will be seen—in us. They must see it in you and in me. Do you go around with a long face as if the world and everything you know are depressing? Or do you go about as one who bears within the Spirit of the living God? The second is your true responsibility. It is by doing that, that you show forth the flavor of Christ and Christianity.

Thirst of the Soul

The third thing that salt does is to make one thirsty. And this leads us to ask: Do you make anyone thirsty for Jesus Christ? The non-Christian tends to feel self-satisfied even if he is not, and he naturally goes through life telling himself that circumstances are wonderful. But when a Christian comes into his sphere of vision, there should be that evidence of joy, satisfaction, and peace that makes him look up and say, “That’s what I want; that is what I want to be like!” Can that be said of you? Do you make men thirsty for Jesus Christ?

In ancient times during the Feast of Tabernacles in the city of Jerusalem it was the custom for the priests to go to the pool of Siloam each day and to return bearing large containers of water that were then emptied upon the altar in the temple. This happened for seven days during the feast. On the last day the ceremony was repeated seven times. On that day, during the Feast of Tabernacles in the year that he attended, Jesus Christ stood up and cried in a loud voice, “If a man is thirsty, let him come to me and drink. Whoever believes in me, as the Scripture has said, streams of living water will flow from within him” (John 7:37–38). It is true, Jesus Christ can satisfy the great thirst of the human soul. Your responsibility is not to satisfy the thirst yourself, but to point men to Jesus Christ. If you do that, out of you will flow his life and character, and others will see him and be satisfied.

A Common Substance

I am sure you already have anticipated the last point of this study, for you have doubtless recognized that salt is one of the most common things of life. It is found everywhere. And hence, when Jesus said, “You are the salt of the earth,” he was saying, “I delight to use little things.” He did not say, “You are the gold of the earth.” He did not say, “You are the uranium of the earth.” He did not even say, “You are the lead,” although Christians sometimes resemble lead far more than we like to admit. He said, “You are the salt”—a common substance. It is from the common things—from the weak, the foolish, the despised, the things that are not (1 Cor. 1:26–29)—that God brings the greatest glory to his name.

We see that throughout Scripture. When God made man in the Garden of Eden, what did he use? Gold? Silver? Iron? No, he used dust. But he breathed into the dust the divine breath of life. When God spoke to Moses in the desert to call him to come forth to be the deliverer of the people of Israel from Egypt, how did he reveal himself? In a dazzling theophany? In thunder and lightning? In an overpowering vision? No, he revealed himself in a burning desert bush. When God called David to deliver the Israelites from the Philistine tyranny, did he make use of Saul’s armor? No, he used a sling and a few small stones. And when Jesus Christ was born, God did not allow him to be born in the courts of the Caesars or of a woman of noble ancestry and great culture. He chose a peasant girl, who was probably illiterate, and she gave birth to Jesus Christ in a stable.

God uses the small things and the small people. God uses you and me that he might do his work in the world. As a matter of fact, the smaller you can become, the more effective his work in you will be. Do you know what we are to be? We are to be picture frames within which Jesus Christ is to be seen. God is not interested in its being a gold frame or a beautifully carved frame. He is just interested in its being an empty frame, because he knows that when you come to him with that, he can put Christ there. And when people look at you, they will see Jesus.[2]


13 Salt and light are such common substances (cf. Pliny, Nat. 31.102: “Nothing is more useful than salt and sunshine”) that they doubtless generated many sayings. Therefore it is improper to attempt a tradition history of all gospel references as if one original stood behind the lot (cf. Mk 4:21; 9:50; Lk 8:16; 11:33; 14:34–35). Equally, the suggestion that Jesus is referring to the “covenant of salt” (Lev 2:13; Nu 18:19; 2 Ch 13:5) seems unlikely. Where that expression shows up in the OT, it seems to be connected with the permanence or stability of God’s covenant with his people. Here, however, Jesus says that his disciples are “salt.” There is no mention of covenant, and, far from symbolizing stability, the salt of which Jesus speaks loses its effectiveness.

The reality is that “salt” is not a technical word with only one set of associations. It can even be connected with judgment (Lot’s wife is turned into a pillar of salt, Ge 19:26; one might ruin an enemy’s field by sowing it with salt, Jdg 9:45). Salt was used in the ancient world to flavor foods and even in small doses as a fertilizer (cf. Eugene P. Deatrick, “Salt, Soil, Savor,” BA 25 [1962]: 44–45, who wants tēs gēs to read “for the soil,” not “of the earth”; but notice the parallel “of the world” in v. 14). Sometimes the word is simply referring to a commodity (Ezr 6:9) or identifies a place (2 Sa 8:13). Above all, salt was used as a preservative. Rubbed into meat, a little salt would slow decay. Strictly speaking, salt cannot lose its saltiness; sodium chloride is a stable compound. But most salt in the ancient world derived from salt marshes or the like rather than by evaporation of salt water, and therefore contained many impurities. The actual salt, being more soluble than the impurities, could be leached out, leaving a residue so dilute it was of little worth.

In modern Israel, savorless salt is still said to be scattered on the soil of flat roofs. This helps harden the soil and prevent leaks; and since the roofs serve as playgrounds and places for public gathering, the salt is still being trodden under foot (Deatrick, “Salt, Soil, Savor,” 47). This explanation negates the attempt by some (e.g., Lenski, Schniewind) to suppose that, precisely because pure salt cannot lose its savor, Jesus is saying that true disciples cannot lose their effectiveness. The question “How can it be made salty again?” is not meant to have an answer, as Schweizer rightly says. The rabbinic remark that what makes salt salty is “the afterbirth of a mule” (mules are sterile) rather misses the point (cf. Schweizer). The point is that if Jesus’ disciples are to act as a preservative in the world by conforming to kingdom norms, if they are “called to be a moral disinfectant in a world where moral standards are low, constantly changing, or nonexistent …, they can discharge this function only if they themselves retain their virtue” (Tasker).


13 The verb μωρανθῇ (mōranthē, “loses its saltiness,” GK 3701) is used four times in the NT. In Luke 14:34, it again relates to salt, but in Romans 1:22 and 1 Corinthians 1:20, it has its more common meaning “to make or become foolish” (cf. cognate μωρέ [mōre, “fool”] in v. 22). It is hard not to conclude that disciples who lose their savor are in fact making fools of themselves. The Greek may hide an Aramaic תפל (tpl, “foolish”) and תבל (tbl, “salted”; see Black, Aramaic Approach, 166–67).[3]

[1] MacArthur, J. (2008). Daily readings from the life of Christ (p. 93). Chicago: Moody Publishers.

[2] Boice, J. M. (2002). The Sermon on the Mount: an expositional commentary (pp. 61–66). Grand Rapids, MI: Baker Books.

[3] Carson, D. A. (2010). Matthew. In T. Longman III & D. E. Garland (Eds.), The Expositor’s Bible Commentary: Matthew–Mark (Revised Edition) (Vol. 9, pp. 168–169). Grand Rapids, MI: Zondervan.


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