John Stott is correct, I think, when he points out that whereas the Beatitudes teach us about Christian character, these verses teach us about a Christian’s influence in the world. The lesson is straightforward: those who have the character described in the Beatitudes become as an inevitable consequence salt and light in this world. First of all, he tells us that they are salt. Though today we use salt mainly as a flavoring agent, in Jesus’ time salt was also used as a preservative against decay. In an age before refrigeration, if you wanted meat to last, you salted it. If meat is properly cured, it can evidently last a long time. In a similar fashion, the disciples are to act as a moral preservative in a corrupt and godless age. As R. V. G. Tasker put it, they are “called to be a moral disinfectant in a world where moral standards are low, constantly changing, or non-existent . . . they can discharge this function only if they themselves retain their virtue.”
But this is not all Jesus has to say. It is not only, “You are the salt of the world,” but he goes on to say, “But if the salt has lost its savor, wherewith shall it be salted [i.e. how shall it become salty again]? It is thenceforth good for nothing but to be cast out and to be trodden under foot of men.” What is he saying? He is saying that when a Christian ceases to function as salt in the world, they are just useless. A salt without its savor is useful neither for flavoring nor is it useful as a preservative. You just cast it out into the streets.
It should be pointed out that sodium chloride is a stable compound and therefore in the strictest sense salt cannot lose its saltiness. However, the salt that Jesus refers to in this Sermon “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.” Both the salt itself and its residue were called salt, so that Jesus could speak of salt that had lost its saltiness. In fact, “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.”
So this is not just a function of a Christian, it is the function of a Christian in this world. Disciples who don’t live in a such a way to influence their generation against the evils of the day are useless to the world in which they live, they are useless to the church in which they profess to belong, and they are useless to the God they claim to serve.
This role though, is mostly negative. It is the role of salt to stop decay; it is the role of a Christian to live in such a way that the corruptions of the society in which they dwell are minimized. We are to serve as a restraining influence. But we are to be more than that. So Jesus goes on to describe the Christian as light. “You are the light of the world. A city that is set on a hill cannot be hid; neither do men light a candle and put it under a bushel but on a candlestick and it gives light to all that are in the house.”
This is something positive. As salt, the believer is meant to push back on the evil in the world. As light, the believer is meant to attract people to the truth. Paul wrote to the Philippian Christians, “Do all things without grumbling or questioning, that you may be blameless and innocent, children of God without blemish in the midst of a crooked and twisted generation, among whom you shine as lights in the world, holding forth the word of life” (Phil. 2:14-16). The idea is clear enough: just as there is something attractive about the nature of light, so there should be something about the life of a Christian, both in words and works that should attract those who dwell in darkness. If you are a weary traveler on a long road and darkness is falling, and on a hillside you see a city shining out of the darkness, you are probably going to feel a certain degree of gladness in your heart that there is a place you can rest in safety. Even so, the believer is to live the kind of life that will attract those who, seeing the darkness in which they live, will come to him/her for direction and guidance.
Our Lord then goes on to explain exactly what he means by the disciple shining as a light on a hill: “Let your light so shine before men that they may see your good works and glorify your Father who is in heaven.” In other words, we shine through our good works. Or, another way to put it is that we shine by manifesting day in and day out the works that come from a character described by the Beatitudes.
The reason for this is that men would see our good works and then glorify God. We are to live for the glory of God in all that we do, for only then will our lives truly point away from ourselves and to the God that all men need. It is easy to live in such a way that we do good things but do them so that people look at us instead of to God. This was the mistake of many of the religious people of Jesus’ day: “They do their works to be seen of men” (Mt. 23:5). They tithed, prayed, and fasted so that they would be glorified (Mt. 6:1-18). But that is such a mistake! For the only light we have is a reflected light.
It is the mark of a truly God-centered life that people look past you to God. A religious life that is man-centered has no problem getting people to praise it for the good deeds that it does. But it is only the person whose life is truly God-centered that is also really supernatural so that nothing can explain it except the grace and power of God. What has caught the eyes of the unbelievers through the ages? Is it not that they saw in believers something that could only be explained by something outside of them? If the world looks at us and sees something which they can duplicate, then we are not shining our light. It will not be attracted to us. On other hand, if we are living in such a way that only God can explain, then we are shining brightly. But that will only happen if we are living for the glory of God and not for ourselves.
The teaching of Jesus then, is this. Those who are his disciples are described by a certain set of character traits. But these traits are not meant to be hidden. They are meant to be displayed in our lives by the things that we say and do. As we live out being poor in spirit, and meekness, and hungering and thirsting for righteousness, and mercifulness, and purity, and a peacemaking spirit, then we will be the salt of the earth and the light of the world. Men will see our good works and glorify our Father in heaven.
There are some principles that emerge from this text. The first is that the Christian is radically different from this world. Salt is different from that which it flavors or preserves. Light is the opposite of darkness. We cannot affect any change in this world in which we live if we are like it. If we are like the world, if we share its tastes and preferences and values, then we do not belong to Christ. “Such were some of you” is the eternal description of the believer (1 Cor. 6:11). Peter wrote to the Christians of his day, “But you are a chosen race, a royal priesthood, a holy nation, a people for his own possession, that you may proclaim the excellencies of him who called you out of darkness into his marvelous light. Once you were not a people, but now you are God’s people; once you had not received mercy, but now you have received mercy” (1 Pet. 2:9-10).
The second principle is that the Christian is part of this world. This may seem strange to say, given what I’ve just been saying, but it’s true. It’s the paradox of the Christian life. We are in this world but we are not of it. After all, you cannot be an influence in the world if you aren’t in it. Christ does not call us to separate from this world completely; he does not call us to withdraw into our Christian ghettos. We are to be separate in the way we live, but not where we live. To withdraw from the world is to do exactly what Jesus says we must not do. It would be to put our light under a bushel. It would be to become tasteless salt, affecting no change, stopping no decay. It would be therefore to completely deny the Christian position with regard to the world and our witness to it.
The third principle is that the Christian is to be intentional in living out a life of witness to the world. This surely is the force of verse 16: “Let you lights so shine among men that they may see your good works and glorify your Father who is in heaven.” We are not just to shine our light but we are to so shine it that others see it. That doesn’t mean that we become ostentatious in our presentation. It doesn’t necessarily mean that you stand on a street corner and preach the gospel – although God certainly does call some to this work. But it does mean that we have an eye out for the lost who are around us. It means that we care about the people we live and work with. It means that life is more than just ourselves and our problems. It means that we stop living life selfishly. It means that we care about God’s global mission to advance his kingdom and exalt his name among the nations.
The question therefore is: how do we live this out? In some sense, the answer is pretty straightforward. You live like salt and light in this world by living out the Beatitudes in your life. But if you’re like me, you are probably tempted to read things into this passage that actually end up undoing it in your life.
What I mean is that when I read this passage, and think of being salt and light in this world, being a city on a hill, I begin to think only of things on the level of the grand and glorious. And I’m not alone. When John Winthrop preached his famous sermon “A Model of Christian Charity” in 1630 on his way to found a new settlement in the New World, he used the words of Christ to express the greatness and breadth of his vision: “For we must consider,” he said, “that we shall be as a city upon a hill. The eyes of all people are upon us.” This political sermon and these words have been picked up by many politicians since, including Presidents Kennedy and Reagan. So I ask you: when you read the words “city upon a hill,” knowing that Christ calls you to this, what comes to mind for you?
For many of us, what comes to mind is something like feeding homeless orphans in India, or preaching the gospel to Muslims in Africa, or doing some kind of obvious missionary or charitable work.
I’m not even beginning to suggest that doing these things is wrong. I thank God that he calls women like Amy Carmichael who gave her life to rescue young women in India from prostitution. I sincerely hope that he calls some of these young men and women in this congregation to give their lives on the mission field. In fact, we ought all of us to be willing to pack up and go to any mission field that God has called us to.
But that’s just the thing. For most of you, the mission field is right here, in Texas, in your homes and neighborhoods and workplaces. My point is this: if all you can think about is some grand mission on a foreign field when you read these words, knowing that right now that is just not going to happen given where you are in life, then you are going to miss what God has called you to do today. He may be calling you to be salt and light in Bangladesh. And if he is: Go! But one thing is for sure: God is calling you to be salt and light in your own living room surrounded by your children. He is calling you to be salt and light at the workplace, wherever that is.
We’re living in a day when the call to be radical has become so commonplace that it is no longer radical. The radicals have become the conservatives. But one thing I’m worried about is that the call to be radical is misunderstood to imply that living out the Christian life anywhere except the inner city or foreign mission field is somehow wrong. Being a city on a hill doesn’t just happen in soup kitchens. Most often it happens in the day to day occurrences as we live out a life of obedience to Christ among our families, friends, and co-workers.
In his book, Ordinary: Sustainable Faith in a Radical, Restless World, Michael Horton tells the story of a young woman, Tish Harrison Warren. When she was 22 years old, she went on a mission trip to Africa, and became known as a “radical” Christian by people in her church, but almost immediately begin to struggle with what that was supposed to mean for her life. Horton writes, “After spending time in various ‘radical’ Christian communities, Warren began to wonder if ordinary life was even possible.” Then, about 10 years later, she came to this realization:
Now I’m a thirty-something with two kids living a more or less ordinary life. And what I’m slowly realizing is that, for me, being in the house all day with a baby and a two-year-old is a lot more scary and a lot harder than being in a war-torn African village. What I need courage for is the ordinary, the daily every-dayness of life. Caring for a homeless kid is a lot more thrilling to me than listening well to the people in my home. Giving away clothes and seeking out edgy Christian communities requires less of me than being kind to my husband on an average Wednesday morning.
As Horton puts it, “Sometimes, chasing your dreams can be ‘easier’ than just being who we are, where God has placed you, with the gifts he has given to you.”
But, as he goes on to point out, this does not mean being mediocre. We ought to strive for excellence in what God has called us to do. We ought to be salt and light, to be a city on a hill in the context in which we’ve been placed. But that’s just the thing. If we can’t think of anything else when it comes to the call to be a city on a hill except a dream we cannot attain, at least not at the present, then we are not going to put our energies into being salt and light to the best of our abilities in the here and now.
What motivates our dreams, anyway? Is it the praise of man or the praise of God? It’s not going to win you a lot of attention by living an ordinary life of obedience to God. But maybe that’s what God has called you to do. And in the end, that’s all that matters. It’s his glory, not our own, that we ought to be aiming for, anyway. Paul says that the mark of a regenerate man, whose heart has been changed by the Spirit, is that “his praise is not from man but from God” (Rom. 2:29).
And by the way, you don’t know what God can do with an ordinary life that is also salt and light. I heard a great story this week of an ordinary man who just witnessed to people as God gave him opportunity. His witness was simple and often just a few words, but as people would reflect later on what he had said to him or read the tract he gave to them, they would become convicted and end up being saved. Many of these people joined a particular church in town. As the pastor spoke to them, and asked how they had come to be a part of the church, they all spoke of this quiet man who witnessed to them. So the pastor sought him out. It turns out he came from another nearby town, and when the pastor finally tracked him down, and told him the stories of the people that had been saved through this man’s witness, tears began to stream down his face. He told the pastor, “You’re the first person who’s ever told me that I’ve done something good for God’s kingdom.” He had been utterly oblivious to the fruits of his witness. But God had blessed it, nonetheless.
God isn’t interested in The Next Big Thing. And if you spend your life moving from one adrenaline rush to the next eventually you are going to wear yourself out. And the sad thing is, it’s probably not for God’s glory, but for your own excitement and glory. Instead, God commands you to let your light shine where you are even in the mundane so that men see your good works and glorify your Father in heaven.
All of this to say that the main thing to being this kind of person is to resist the discontentment with the place where God has placed you. Resist the restlessness that plagues the world around you. It is restless precisely because it does not know a sovereign and saving God who knows his people and never leaves them. Be free to be radical in the eyes of Jesus while being ordinary in the eyes of the world.
And then the second thing is to always have God’s glory before your eyes. If we are not serving him, then we are only going to want to be salt and light when there are obvious returns on our labor. But faithfulness cannot be sustained only by results. It takes an eye to the honor of our Lord. Calvin, when he was banished from an ungrateful Geneva after his service there, said, “Surely if I had merely served man, this would have been a poor recompense. But it is my happiness that I have served him who never fails to reward his servants to the full extent of his promise.” And it was this eye to God’s glory that enabled Calvin to go back to Geneva after three years of exile!
But then of course, we must always remember that being light in our community only happens through Christ. Our light is a borrowed light. We are lights to the world because Jesus is the light of the world (Jn 1:9). We can only reflect his light. We don’t hold out to the world the message that we are the answer. The believer is not the answer to this world’s darkness. The church is not the answer. Only Christ is the answer, and it is only as men and women come personally into contact with his saving benefits through faith in him and repentance from sin that they too share in his light and become light to others. For the main problem with the world, what leads to its moral putrefaction, is sin. And sin can ultimately only be dealt by redemption: redemption from the guilt and grip of sin. Jesus alone is the redeemer of mankind. He alone can forgive your sins and give you real freedom from its power, and it is our privilege as salt and light to point men and women to the Lord Jesus Christ.
 John Stott, The Message of the Sermon on the Mount (BST), p. 57, ff.
 R. V. G. Tasker, The Gospel According to St. Matthew (TNTC), p. 63.
 D. A. Carson, Matthew: 1-12 (EBC), p. 138.
 Horton, Michael S. (2014-10-07). Ordinary: Sustainable Faith in a Radical, Restless World (p. 15). Zondervan. Kindle Edition.
 Ibid, p. 16.
 Cf. Ibid, p. 67,ff.