Sermon Transcript

Introduction

Are you a citizen of the kingdom of heaven? Are you a citizen of the city of God? Or are you a citizen of the city of man, the city destined for destruction? That is the overarching question I want us to consider this morning? There will be other questions, but we will come back to that one at the end.

Last week, we delved into the final two Beatitudes—peacemaking and enduring persecution for righteousness—unpacking the radical character Jesus expects of His followers. This week, we shift our focus to the next section of the Sermon on the Mount’s introduction (Matthew 5:13–16). Here, Jesus moves beyond describing who His disciples are to revealing what they do—how they bear witness to a world that often stands in opposition to God and His purposes.

Think about what happens when you drop a Mentos into a bottle of Coke, pour water into hot oil, or mix vinegar with baking soda. Each of these reactions is immediate, dramatic, and impossible to ignore. In the same way, when citizens of the kingdom—those who embody the ideals of Christ—are introduced into a world that resists God and His purposes, a reaction is inevitable. Something has to happen.

Picture this: you toss a Mentos into a Coke bottle, and… nothing. No fizz, no spray. You’d scratch your head and wonder, “Is this really a Mentos? Or is the Coke flat?” Something’s wrong—either the candy lacks its reactivity, or the soda’s lost its gas. Jesus makes a similar point in Matthew 5. When kingdom citizens—shaped by poverty of spirit, meekness, mercy, and purity—collide with a world marked by pride, greed, and darkness, two reactions should occur: preservation and illumination. If they don’t, something’s off. Either the disciples aren’t living as kingdom citizens, or the world’s influence has dulled their distinctiveness. Jesus expects a response—His followers are meant to provoke a reaction, not blend into the background.

To drive this home, Jesus turns to two staples of first-century life: salt and light. For His audience—fishermen, farmers, and villagers—these were as familiar as water or bread. Salt preserved fish in a world without refrigeration, seasoned bland meals, and held value in trade and ritual (think of the “covenant of salt” in Leviticus 2:13). Light, from a flickering oil lamp or a hilltop town glowing at night, pierced the darkness, guided weary travelers, and signaled safety. His disciples would have grasped the comparison instantly: they were to be as essential and impactful as these everyday materials. What’s remarkable is that salt and light remain relevant today—still staples in our homes, still carrying the same properties—and Jesus’ message rings as clear now as it did then. Through these metaphors, He reveals the dual role of His followers in a broken world.

Let’s begin by observing that when kingdom citizens meet the world, they are called to be:

• Agents of Preservation and Purity (v. 13): Like salt, they prevent moral and spiritual decay, enhancing life with God’s goodness.
• Agents of Illumination (vv. 14–16): Like light, they shine truth and love into darkness, guiding others to glorify God through their visible good deeds.
• Main Point: The true citizens of the kingdom of heaven preserve and illuminate the world.

These aren’t optional traits—they’re the natural outcome of kingdom life meeting a fallen world. Just as Mentos and Coke can’t coexist without a reaction, kingdom citizens and a godless culture can’t meet without preservation and illumination breaking forth. If the salt loses its savor or the light hides under a basket, the problem isn’t the world’s resistance—it’s the disciples’ failure to live out their calling. Jesus’ metaphors set the stage for a witness that’s both subtle yet pervasive (salt) and bold yet God-centered (light), a reaction as inevitable as vinegar hitting baking soda.

As we dive into this passage, let us consider what it truly means to be salt and light—and whether our lives reflect the transformative impact Jesus intends us to have. Let’s look first at what it means to be…

Agents of Preservation and Influence (v. 13)

Jesus starts with a striking image: “You are the salt of the earth” (v. 13). He’s speaking to His disciples—those who embody poverty of spirit, meekness, and mercy—and by extension, to us. Salt of the earth. It’s a phrase worth unpacking, and three truths rise to the surface.

1. Preserving and Influencing the World 
   Christians aren’t passive—they’re agents of preservation and influence. Jesus doesn’t say, “Let the world shape you.” No, He flips it: you shape the world. Salt keeps meat from rotting; disciples keep society from total decay. Why? So the gospel—the Good News of Jesus—can spread before everything spoils.
   Illustration: You’ve smelled it—that stench when meat sits out too long, festering in the heat. Disciples stop that kind of moral rot, holding back the world’s stench with God’s grace.
2. A Distinct Identity 
   Salt isn’t the meat it preserves—it’s different. Jesus draws a line here: kingdom citizens stand apart from the world they engage. Think of Augustine’s City of God versus the City of Man. We live by a higher calling—humility, not pride; mercy, not greed—seasoning a culture that’s lost its taste.
3. Contact Matters 
   Salt on a shelf won’t save meat—it has to touch it. Preservation demands contact between God’s people and the world.
   Illustration: Drop a Mentos into a Coke bottle, and boom—a reaction. No drop, no fizz. Christians must engage—through work, friendships, service—to preserve. Stay distant, and nothing changes.

This metaphor lands perfectly. Jesus “is concerned [about] that society be preserved from worsening corruption so that time and opportunity are given for repentance through the preaching of the gospel” (cf. John Stott, The Message of the Sermon on the Mount, 1978, p. 58). The church doesn’t just hold back decay—it flavors life with the gospel’s hope. But there’s more. Alongside preservation, Jesus calls us to be…

Agents of Illumination (v. 14) 

“You are the light of the world,” He says next. Salt works quietly; light shines boldly. Both were everyday staples—salt in their kitchens, lamps in their homes—and they still are for us. Light runs deep in Scripture: God is light (1 John 1:5), Jesus is light (John 8:12), and now we’re called to shine. But what does “light of the world” mean? It’s woven throughout the Bible: the Messiah and His people manifesting God’s glory, bringing salvation to the nations. Two insights emerge.

1. Reflecting Christ’s Light 
   We don’t generate our own glow—we reflect Jesus. Matthew 4:16 says, “The people dwelling in darkness have seen a great light,” fulfilled when Jesus proclaimed the kingdom. Now, that light beams through us. Like a lamp lit by His flame, we carry His truth and love into the shadows.
2. Rooted in Israel’s Purpose 
   This isn’t a spur-of-the-moment metaphor. Jesus isn’t riffing off the cuff—He’s tapping Israel’s story. The lampstand in the tabernacle and Temple (Exodus 25:31–40) glowed as God’s presence, shining out to the nations. Isaiah 49:6 declares, “I will make you as a light for the nations, that my salvation may reach to the end of the earth”—a call fulfilled in Jesus and now ours. Revelation sees churches as lampstands too (Revelation 1:20), radiating Christ’s light. Israel’s faith was meant to draw others near, and so is ours.

Salt and light together paint a vivid picture. Salt is simple yet powerful—preserving, seasoning. Light is captivating yet clear—illuminating, guiding. But how do we live this out? How do we salt the earth and light the world? It hinges on three realities.

How to Salt and Light the World 

1. The Sequence of Salt and Light 

Why salt first, then light? Jesus could’ve swapped them, but the order’s deliberate. Salt is who you are—your inner life, your purity. Light is how you shine—your outward witness. Before your light can glow, your salt must savor. Salt purifies within; light radiates out. If we’re not savory, we won’t shine.
Get this backwards, and you see today’s evangelical mess. Churches fixate on deeds—rushing to look loving, bending over to seem caring. But too often, the inner life’s neglected. Sin’s shrugged off as a “mistake,” not a call to holiness. Jesus says: be salt first. That’s what makes us distinct.
Some say, “Talk sin or God’s standards, and you’ll push people away.” Jesus says the opposite: our distinctiveness—hungering for God, chasing righteousness, purity of heart—pulls people in. The world’s full of empty pursuits; they don’t need our imitation. If we live like them, they’ll ask, “Why bother?” But when they see us desperate for God’s presence, their chasing looks hollow—and ours looks alive.

Illustration – Early Church Witness:

• Love That Stunned:
  • Tertullian (c. 160–225 AD) wrote, “It is mainly the deeds of a love so noble that lead many to put a brand upon us. ‘See,’ they say, ‘how they love one another!’” (Apology, 39).
  • Emperor Julian moaned, “The impious Galileans support not only their own poor but ours as well” (Letter to a Pagan Priest, c. 361 AD).
• Purity That Shone:
  • The Epistle to Diognetus (2nd century) says, “They marry, as do all others… but they do not destroy their offspring” (5).
  • Rodney Stark notes this built stronger communities (The Rise of Christianity, p. 126).
• Courage That Drew:
  • Tertullian said, “The blood of the martyrs is the seed of the church” (Apology, 50). Eusebius saw conversions from their steadfastness (Ecclesiastical History, 8.1).
• Conclusion: Christianity grew not by power but by salty lives shining bright.

2. Heed the Warning: Don’t Lose Your Salt or Hide Your Light 

Jesus warns twice: “If salt loses its taste, how shall its saltiness be restored?” (v. 13). And, “No one… puts [a lamp] under a basket” (v. 15). Lose your salt, and you can’t season. Hide your light, and you can’t shine.

• How Do You Lose Saltiness?
  When you prioritize holiness for others over your own personal holiness. Both matter, but one’s first.
  • We focus on the holiness of others: We have the Davidic syndrome. We are quick to judge, but slow to change, slow to seek holiness.
  • We focus on cultural holiness: The biggest problem with the Pharisees is that they prioritized holiness for others over their own.
• Questions:
  • But do we guard our hearts with that zeal? We obsess over “out there” and ignore the vices “in here.” That’s when salt goes flat.
    Why’s our witness feeble? Why don’t we stand out? We’ve lost our salt—our distinctiveness.
• Observation:
  • If we’re just Sunday-goers who give more cash, why would anyone join? But if we’re gripped by God, surrendered to His mission, we shine naturally.
• How Do You Hide Your Light?
  Why dim your glow? The sequence explains it: salty lives yield good works; unsalty lives don’t. If my life’s meant to point to God but doesn’t match, I’d hide too—no one wants a spotlight on a mismatch.
  • Illustration: At Moody Bible Institute, I did 4 a.m. building checks. I’d flick my flashlight on, then off quick. Why? Alone in a dark Chicago alley, I didn’t want eyes on me. You hide your light when your life’s not congruent with the kingdom. But when you’re salty, you shine—no fear.

3. Salt and Shine: Heart Work and Handwork 

• Heart Work: Stay Salty 
  Today, salt is stable—but in Jesus’ day, impurities dulled it. Skip heart work, and we dull too. The Greek for “loses its taste” fundamentally means “foolish”—like the fool who ignores the words of Jesus and built his house on the sand of disobedience that is at the end of the Sermon on the Mount. In other words, losing saltiness is disobeying Jesus. And just like that there was a great ruin for the fools house, so will there be great ruin if we lose our saltiness. Jesus says that unsalty salt is thrown out and trampled by men.
  Proverbs 4:23–27 guides us: “Above all else, guard your heart.” Watch your:
  • Heart: Root out idols—greed, pride.
  • Lips: Speak grace, not grumbling.
  • Eyes: Don’t drift to envy or lust.
  • Feet: Walk obedience, not rebellion.
• Hand work: Shine Bright – Heart work fuels handwork—shining like a city on a hill.
  • Handwork: In life, “handwork” represents our actions, efforts, and the way we engage with the world.
  • Christian handwork:
    • Q & A 86 – slide
      • Q. Since we have been delivered
        from our misery
        by grace through Christ
        without any merit of our own,
        why then should we do good works?
      • A. Because Christ, having redeemed us by his blood, is also restoring us by his Spirit into his image,

1. so that with our whole lives we may show that we are thankful to God for his benefits,
2. so that he may be praised through us,
3. so that we may be assured of our faith by its fruits,
4. and so that by our godly living our neighbors may be won over to Christ.

• • • We are God’s billboards. We advertise his greatness, and power.
      • Jesus says, in verse 16, shine in such a way that people see your good works and glorify God.
      • For we are his workmanship, created in Christ Jesus for good works, which God prepared beforehand, that we should walk in them. – Eph. 2:10
    • How do we bring praise to God?
      • Loving Neighbor:
        • Loving neighbor is the hallmark of Christianity. And loving neighbor begins with us.
          • Some can have more love for their unconverted neighbor than for their brother or sister in Christ.
        • Jesus says, “By this all people will know that you are my disciples, if you have love for one another” (John 13:35).
        • Paul adds in Philippians 2:14–16, where he is exhorting the church to humility and service, this: “Do all things without grumbling… [to] shine as lights” in a twisted world.
        • Romans 12 urges, “Outdo one another in showing honor.” Fight for unity. Be peacemakers. Our world’s divided—everyone’s for themselves, the church is not!
      • Proclaiming Truth: Our good works are not enough. We must have a reason for our good works. We must explain to people why we do what we do.

Gospel Call

Maybe you don’t know this Jesus we’ve praised today. He calls us to be salt and light—holy, loving, pure, compassionate. Look at your life: Is it impure? Self-focused? Have you hurt others chasing your own way? Here’s hope: the Jesus who demands holiness makes us holy. We’re all sinners, God’s enemies by nature. But trust in Jesus—pure, loving, compassionate—and God welcomes you into His family, forgiven. That’s the gospel call today. Trust Him now.

Conclusion

This morning, I began the sermon by asking the question: are you a citizen of the kingdom of heaven, of the city of God, or are you a citizen of the city of man, the city destined for destruction? And as we have explored Matthew 5:13-16, I hope you have been able to answer that question because in those verses we have seen that being salt and light is not an option—it is the natural result of being a citizen of the kingdom of heaven. Just as a bottle of Coke has no choice but to fizz when a Mentos is dropped into it, we cannot help but be salt and light if we truly belong to Christ. This is not a suggestion, nor is it negotiable.

There is no in-between. There is no room for passive Christianity or double-mindedness. We must be salty in our personal holiness, resisting moral decay in our own lives before we can preserve the world around us. We must shine—not out of self-promotion, but through visible, selfless devotion to Christ and His people. Our lives should reflect the reality that we belong to a different kingdom, one that does not blend in with the world but transforms it.

The challenge before us is clear: Will we embrace our calling to be distinct, or will we lose our saltiness? Will we let our light shine, or will we hide it in fear or compromise?

A faith that does not preserve or shine is of no use. But a life fully surrendered to Christ—saturated in holiness and overflowing in love—will inevitably influence those around it. So let us be salt. Let us shine. And may the world see our good works and glorify our Father in heaven.