13 “You are the salt of the earth, but if salt has lost its taste, how shall its saltiness be restored? It is no longer good for anything except to be thrown out and trampled under people’s feet.
14 “You are the light of the world. A city set on a hill cannot be hidden. 15 Nor do people light a lamp and put it under a basket, but on a stand, and it gives light to all in the house. 16 In the same way, let your light shine before others, so that they may see your good works and give glory to your Father who is in heaven. 
The Kingdom of God has come in the person of Messiah Jesus. But its power and influence are visible only in the sphere in which the world least expects to see them. They are visible in the poor in spirit, among those who mourn over sin, and in the persecuted community of the followers of Jesus. It is these who receive the divine benediction.
The Beatitudes, the opening section of the great Sermon on the Mount, climax with the promise of conflict that exists between the Kingdom of God and the kingdom of this world. This world opposes Christ’s people and persecutes them. The true church is too upside-down in its values to be tolerated. So, the world sees the Kingdom of God as a threat to its own ways. At best, it ignores God’s Kingdom and at worst it actively goes to war against it.
If that is how the world, the flesh, and the devil respond to the Kingdom of God, how are we citizens of God’s Kingdom to live in the world? And how can we live in a way that will make an impact for God’s glory among men? Jesus now turns his attention to these questions, having introduced them with a promise of persecution in the close of the Beatitudes.
Jesus uses two pictures taken from the everyday world of his time to illustrate what it means to be a Christian in the world’s pagan society (a society at war with God): we are like salt; and we are like light. Both of these things were every-day essentials in 1st-century Palestine.
SALT OF THE EARTH (13)
Jesus said, “Y’all are the salt of the earth.” It is, like the eight Beatitudes, another indicative mood (a statement of fact), not an imperative (a command). Jesus is not telling his disciples to become something they are not; he is telling them what they are as citizens of his Kingdom. The implication is that they are to be what God has already made them by giving them the powers of his Kingdom. Because these Kingdom powers are internal realities, we can be tempted to think that we can live them in isolation from the world and its potential persecution of upside-down values. But Jesus makes clear in these four verses, flowing from his previous promise of persecution, that it’s impossible to live out the Beatitudes in private.
The first crowning metaphor Jesus employs is that of salt. 13 “You are the salt of the earth, but if salt has lost its taste, how shall its saltiness be restored? It is no longer good for anything except to be thrown out and trampled under people’s feet.”
Jesus spoke these words very early on in his earthly ministry, when he had only a few poor, uneducated followers. Yet his statement is emphatic: you alone or the salt of the earth. Notice that he does not say you are the salt of Israel, or the salt of the region of Palestine. He is laying out a vast universal effect that his followers will have.
One commentator writes:
By means of these two emblems or metaphors the important truth is revealed that those people whom the world—including even the quasi-pious world of scribes and Pharisees—hates most are exactly the ones to whom it owes most. The citizens of the kingdom, no matter how despised they are and how insignificant they may seem to be, they alone, not the scribes and the Pharisees, are the salt of the earth and the light of the world. 
What made salt special in Jesus’ day was not that it was rare. It was in fact a very common mineral. Its value was found in its use. So it is with members of God’s Kingdom. The primary function of salt was its use as a preservative. Even in our own postindustrial age, salt still functions as a preservative. Think of beef jerky. Jesus is teaching his disciples that the world around them is dead meat. It is rotting away. The Apostle John preached that very thing to his fractured congregation in Ephesus:
Do not love the world or the things in the world. If anyone loves the world, the love of the Father is not in him. 16 For all that is in the world—the desires of the flesh and the desires of the eyes and pride of life—is not from the Father but is from the world. 17 And the world is passing away along with its desires, but whoever does the will of God abides forever. 
Jesus was under no illusions about the world apart from himself. He experienced perfect relationship between himself, the Father, and the Holy Spirit. He was present in the earthly paradise of Eden with Adam and Eve. He knew absolutely that the world, left to itself, festers and rots because the germs of evil are present and active in this world east of Eden. God eventually removed nearly the entire population of the world by a great flood. Yet, given another chance, men fell into immediate sin that led after but a few generations to the holocaust of Sodom and Gomorrah.
Scripture is clear that we live in a world that constantly tends towards decay. Many of the Christless systems of the world may look OK, but inside they are rotting away, and it is just a matter of time before they crumble. The church, as salt, retards decay and acts as a preservative in a disintegrating world. Without Christ, humanity is a dead body rotting and falling apart. Without Christ, the world is dead meat.
It is at this point that many modern commentators launch into applications of Jesus statement urging people to promote social change. You may have heard quite a bit of that and maybe it rings true for you. It’s certainly a good way to fill a sermon and ladle on some holy guilt in the process. But, with all due respect, I don’t believe that is our Lord’s point here any more than pronouncing the Kingdom power of peacemaking was a call to interpersonal conflict resolution. Peacemakers declare peace between God and human beings through Christ’s person and work.
In the same way, the Church’s saltiness is a blessing that preserves the entire world system from immediate destruction so that God can continue to call out a people for himself until the full number of the elect have been brought into his Kingdom to glorify himself through blessing and judgment upon those who refuse his offer of peace. Matthew, in the 13th chapter, will record one of Jesus’ judgment parables that teaches this very point:
The kingdom of heaven may be compared to a man who sowed good seed in his field, 25 but while his men were sleeping, his enemy came and sowed weeds among the wheat and went away. 26 So when the plants came up and bore grain, then the weeds appeared also. 27 And the servants of the master of the house came and said to him, ‘Master, did you not sow good seed in your field? How then does it have weeds?’ 28 He said to them, ‘An enemy has done this.’ So the servants said to him, ‘Then do you want us to go and gather them?’ 29 But he said, ‘No, lest in gathering the weeds you root up the wheat along with them. 30 Let both grow together until the harvest, and at harvest time I will tell the reapers, “Gather the weeds first and bind them in bundles to be burned, but gather the wheat into my barn.’ 
We see that principle at work in the Old Testament, in Genesis 18, when Abraham advocates for God not destroying Sodom and Gomorrah. Abraham argues:
Then Abraham drew near and said, “Will you indeed sweep away the righteous with the wicked? 24 Suppose there are fifty righteous within the city. Will you then sweep away the place and not spare it for the fifty righteous who are in it? 25 Far be it from you to do such a thing, to put the righteous to death with the wicked, so that the righteous fare as the wicked! Far be that from you! Shall not the Judge of all the earth do what is just?” 
This is certainly not to say that those who trust into Christ should not seek to do good for their pre-believing neighbors. The saltiest thing you can be in this dark world is to be an others-focused person who extends the love of Christ in a self-focused, self-loving world. Primarily, we do that through our vocations, the jobs God has given us to do – be it as a parent, a teacher, a student, a physician, a member of the armed forces, a day-laborer (like Jesus was), or a volunteer. When you seek to glorify God in the work he gives you to do, you ARE salt preserving the field so the wheat can be harvested from the weeds.
Salt, wherever sprinkled, creates thirst. Christ makes people thirsty for God. As R. Kent Hughes writes, “Whenever anyone encountered Jesus, whether a Pharisee like Nicodemus or an outcast like Mary Magdalene, that person became thirsty for God. Are we salty enough to make people thirsty for Jesus?” Jesus warned, “if salt has lost its taste, how shall its saltiness be restored? It is no longer good for anything except to be thrown out and trampled under people’s feet.”
How can salt become tasteless? One scholar explains:
Unsalty salt is a contradiction in terms (“like water losing its wetness,” Betz); if it is not salty, it is not salt. But salt as used in the ancient world was seldom pure sodium chloride. The “salt” collected around the Dead Sea contained a mixture of other minerals, and it is possible to imagine the true salt content being washed out, leaving a useless residue. In any case, Jesus is not teaching chemistry, and the ludicrous imagery of trying to “salt” that which should itself be the source of saltiness is a powerful indictment of disciples who have lost their distinctiveness and so no longer have anything to contribute to society. The verb [often] translated “becomes tasteless” more literally means “becomes foolish.”
One way we lose our saltiness is simply by abandoning the ordinary means of grace: the Word preached, prayed, sung, and portrayed in the sacraments of baptism and the Lord’s Supper. We can get tired and discouraged and stop coming to church and fellowshipping with Christ and his people. The most common way I see people lose their saltiness is by allowing preachers to burn them out by telling them that to be salty, they must do extraordinary things or “radical things” for Jesus. Existing as a believer in a dark and rotting world IS being salt. Your very existence preserves this world until the final judgment. So, hear what I tell you now.
Dragging yourself to worship when you are tired and exhausted IS an extraordinary thing! It is a radical thing. You don’t have to change the world, or even your neighborhood. You can actually love your pre-believing neighbors just by performing your job for God’s glory, by being faithful to God in the vocation he gives you. What feels like the burden of the law to you is very often gospel to your neighbor in need. God doesn’t need your good works, your neighbor does.
Are you still “salt”? If you don’t feel salty enough, you can be re-salted when you see your impurity of heart, repent, and ask God to demonstrate more of Christ through us. But know that you can feel exhausted and broken, or even perfectly ordinary, and still be salt. You preserve the dead meat of the world simply by existing in it as one of God’s elect, as a stalk of wheat among weeds destined for destruction.
LIGHT OF THE WORLD (14-16)
The next metaphor Jesus uses to describe the citizens of his Kingdom in the kingdom of the world, the flesh, and the devil is, “Y’all are the light of the world.” You may recall that Jesus also calls himself the light of the world.
Jesus self-designation as the light of the world happened the day after a nightly ceremony at the temple called the Illumination of the Temple. The ceremony took place nightly in the temple treasury in front of four huge pillars topped with large torches that held 65 liters of oil each. Attached to each pillar was a ladder. As sunset approached, priests would climb the ladders to carry oil up to the large bowls and light the giant wicks.
It was said that huge flames not only illuminated the temple but the entire city of Jerusalem. After the torches were lit and roaring high above the people, men would dance before them with burning torches in their hands singing songs of praise as Levite’s played harps, liars, cymbals, and trumpets.
The ceremony celebrated the great pillar of fire (the glory cloud of God’s presence) that led people of Israel during their wilderness wanderings and spread its glowing billows over the Tabernacle and, centuries later, over Solomon’s temple. After sunrise, with the charred torches still in place, Jesus lifted his voice above the temple crowd and proclaimed, “I am the light of the world. Whoever follows me will never walk in darkness, but will have the light of life” (John 8:12).
Jesus was identifying himself as the Shekinah Glory of God that had finally come to rest upon the second temple. He was the pillar of fire that blocked the Egyptian army, the glowing cloud that guided his people by day in the wilderness and lit up the night around their camp. He alone is the light of the world! He is the fulfillment of Isaiah’s prophecy, “the people dwelling in darkness have seen a great light, and for those dwelling in the region and shadow of death, on them a light has dawned.” 
He alone is the fulfillment of everything suggested by the glory cloud. And he is everything suggested by the metaphor of light. It is a foundational principle to our way of thinking about verses 14-16.
In declaring himself to be the light of the world, Jesus suggests the equally foundational fact that the world is in darkness. The physical earth is suspended in dark space. The darkness of the world is a spiritual darkness that dominates the entire world system. But the even more terrible realization is that those living in the darkness love it because they are at war with God. The Apostle John put it this way:
And this is the judgment: the light has come into the world, and people loved the darkness rather than the light because their works were evil. 20 For everyone who does wicked things hates the light and does not come to the light, lest his works should be exposed. 21 But whoever does what is true comes to the light, so that it may be clearly seen that his works have been carried out in God.” 
Because Jesus is the light of the world, those trusting into him are also light in the darkness. His statement is emphatic: Y’all alone are the light of the world. Y’all alone have the Kingdom power to shine into the darkness and pronounce my offer of peace. This is an amazing statement, especially considering that when left to ourselves with only our fleshly resources, we are but shadows.
Many preachers love to extend Jesus’ metaphor and explain that when the sun sets, the moon rises and reflects the light of the sun. Thus, the church is like the moon, reflecting the light of Christ. Depending upon the season and the Lord’s purposes, our moon is either full or but a small slip of light. Either way, it reflects the light of Christ.
That is a good illustration as far as it goes. However, our light as believers in a dark world, is more than reflected. We in fact become light ourselves. As Paul wrote to the church in Ephesus (Eph. 5:8), “for you were once darkness, but now you are light in the Lord. Live as children of light.” Our light is still derived from Christ. As Peter says (2 Peter 1:4), we “participate in the divine nature.” As Paul explains in Colossians 1:27, “God chose to make known how great among the Gentiles are the riches of the glory of this mystery, which is Christ in you, the hope of glory.”
The more we expose ourselves to Christ through fellowship with his saints, through meditation in his Word, through prayer, and most particularly through corporate worship, the more we will shine in the darkness by serving our neighbors. Paul put it this way:
Now the Lord is the Spirit, and where the Spirit of the Lord is, there is freedom. 18 And we all, with unveiled face, beholding the glory of the Lord, are being transformed into the same image from one degree of glory to another. For this comes from the Lord who is the Spirit. 
Messiah Jesus further dramatizes the function of light with two examples: a city built on a hill, and a light set in a home. First, believers collectively function like a city lit up at night, like the temple on the temple mount blazing with the torches of the illumination ceremony. He said, “A city set on a hill cannot be hidden.” It was impossible for the city of Jerusalem to hide itself at night. In our modern day, it’s almost impossible to see the stars for all the city lights filling the night sky.
The second example is that of a small clay lamp set inside a house to light up the room. Remember, Jesus is speaking to mostly poor people who live in one room houses, most without windows. The light of the lamp was essential for them day and night. All of us have had the experience of entering a dark room and searching for the light switch. Light reveals things as they really are.
Messiah Jesus’ life was such that men and women were made to feel what they could not feel fully before – their sin, imperfection, and impurity. He made possible a clearer distinction between good and evil. He destroyed our option of comparing ourselves with others to feel more moral. He was and is the perfect standard. He was the living embodiment of God’s holy, perfect Law upon which he will teach in this sermon.
And the Law begins in verse 16, “In the same way, let your light shine before others, so that they may see your good works and give glory to your Father who is in heaven.” This is an imperative; it’s Law. The way we are told to “shine” is through our good (“beautiful,” kalos) works. God doesn’t need them, but your neighbor does. Your neighbors need your works of compassion and caring. For you it’s law. For them it’s gospel.
It’s gospel for them because “they may see your good works and give glory to your Father who is in heaven.” Remember, Jesus has given these two metaphors on the heels of promised persecution. Peter, who heard Jesus’ Sermon on the Mount, summed up this thought in his first letter. So, we’ll close with his command:
Keep your conduct among the Gentiles honorable, so that when they speak against you as evildoers, they may see your good deeds and glorify God on the day of visitation. 
 The Holy Bible: English Standard Version (Wheaton, IL: Crossway Bibles, 2016), Mt 5:13–16.
 Ferguson, 55.
 Id., 56.
 William Hendriksen and Simon J. Kistemaker, Exposition of the Gospel According to Matthew, vol. 9, New Testament Commentary (Grand Rapids: Baker Book House, 1953–2001), 282.
 The Holy Bible: English Standard Version (Wheaton, IL: Crossway Bibles, 2016), 1 Jn 2:15–17.
 The Holy Bible: English Standard Version (Wheaton, IL: Crossway Bibles, 2016), Mt 13:24–30.
 The Holy Bible: English Standard Version (Wheaton, IL: Crossway Bibles, 2016), Ge 18:23–25.
 Hughes, R. Kent. The Sermon on the Mount: The Message of the Kingdom (Preaching the Word). Crossway. Kindle Edition.
 France, 174–175.
 Hughes, op. cit.
 The Holy Bible: English Standard Version (Wheaton, IL: Crossway Bibles, 2016), Mt 4:16.
 The Holy Bible: English Standard Version (Wheaton, IL: Crossway Bibles, 2016), Jn 3:19–21.
 The Holy Bible: English Standard Version (Wheaton, IL: Crossway Bibles, 2016), 2 Co 3:17–18.
 The Holy Bible: English Standard Version (Wheaton, IL: Crossway Bibles, 2016), 1 Pe 2:12.