Walk in the Light (1 John 1:5-10)

This sermon was preached on April 30, 2017 by Brian Watson.
Sermon recording
PDF of typescript (not a transcript of the recording, but the written sermon that was prepared in advance).

Do you know why so many people are miserable? I’m sure there could be many answers to that question. One is that, in this life, we experience great loss. Bad things happen. Dreams are dashed. Life ends in death. But I think a real answer is that we are so often in darkness. We hide our true selves. We feel isolated from one another. We feel separated from God. How can we have real joy? How we can experience real life, eternal life? We must come into the light.

That’s what we’re going to talk about today. But first, I want to give us a bit more of an introduction to a book of the Bible we started looking at last week. Last week, we started to look at a book in the New Testament called 1 John. We don’t know exactly when this letter was written, but it was surely written toward the end of John’s life. John was one of the original followers of Jesus. He had heard Jesus teach. He had seen Jesus’ miracles. He had seen Jesus die. And he saw Jesus and even touched him after Jesus rose from the grave. John was an apostle, one of Jesus’ specially authorized messengers. And John had some important things to communicate to Christians, which is why he wrote this letter.

First John was probably written to churches in and around Ephesus, a city in the area of the world that is now known as Turkey. Perhaps one of the reasons why John wrote this letter is because he sensed that he was getting close to the end of his life. He had some important things he wanted to share with these Christians, and that’s why he wrote. But another reason that John wrote was that there had been false teachers in these churches. There’s a hint of this throughout the whole letter. These teachers believed different things about Jesus and what it meant to be a disciple of Jesus. The clearest hint of this is in 1 John 2:18–19, which says,

18 Children, it is the last hour, and as you have heard that antichrist is coming, so now many antichrists have come. Therefore we know that it is the last hour. 19 They went out from us, but they were not of us; for if they had been of us, they would have continued with us. But they went out, that it might become plain that they all are not of us.[1]

There were people in the churches John wrote to who had left, because they were “anti-Christ.” They were literally against Jesus because they had different views of Jesus. They didn’t know the true Jesus and they didn’t live as true Christians. So, John wants his readers to know who Jesus really is, what he really did, and what it means to be a real Christian.

Also, as I said last week, John wants his readers to be sure that they are Christians. He realizes there’s a false brand of Christianity out there. So, toward the end of the letter we read, “I write these things to you who believe in the name of the Son of God, that you may know that you have eternal life” (1 John 5:13).

How can we know that we have eternal life, a life of light? That’s a theme that we’ll continue to look at as we explore this important letter. Today, we’re going to look at 1 John 1:5–10. Since this is a short passage, we’ll read the whole passage and then I’ll go back it in more detail. So, here is 1 John 1:5–10:

This is the message we have heard from him and proclaim to you, that God is light, and in him is no darkness at all. If we say we have fellowship with him while we walk in darkness, we lie and do not practice the truth. But if we walk in the light, as he is in the light, we have fellowship with one another, and the blood of Jesus his Son cleanses us from all sin. If we say we have no sin, we deceive ourselves, and the truth is not in us. If we confess our sins, he is faithful and just to forgive us our sins and to cleanse us from all unrighteousness. 10 If we say we have not sinned, we make him a liar, and his word is not in us.

How does John begin his message? He starts with God’s character. God is light, and in him there is no darkness. You might think he would start off with, “We’re all a bunch of sinners and God is angry with us.” But he begins with God’s character. The message that John heard from Jesus is that God is light, and in him there is no darkness.

What does it mean for God to be light? I think we can think of this in at least four ways. One, God is brilliant. We talk about God’s glory, and one of the ideas behind the word “glory” is God’s brilliance. When Jesus was born, an angel announced his birth to shepherds. In Luke’s Gospel, we read, “And an angel of the Lord appeared to them, and the glory of the Lord shone around them, and they were filled with great fear” (Luke 2:9). The night sky was filled with light, the “glory of the Lord.” God is radiant, brilliant, gleaming. He is glorious.

Two, God is the source of life. The light of the sun brings life. If the sun somehow stopped shining, within a matter of days, the earth would be too cold for us to live on. Photosynthesis would stop and plant life would start to die. We need the light of the sun to live. Likewise, God is the source of life.

Three, God reveals truth. God is the source of truth. Jesus said that he himself is truth (John 14:6). The presence of light in this room allows us to see things as they really are. (Or, the light in this room allows us to see how things look in this light. Colors can look different based on the type of light.) When people say, “I’ve seen the light,” they mean they’ve come to know the truth. That’s why people in cartoons have light bulbs appear in those thought bubbles when they have an idea.

I think it’s important to see that God is the truth that makes sense of everything else. C. S. Lewis once wrote, “I believe in Christianity as I believe the sun has risen, not only because I see it, but because by it I see everything else.”[2] The light of God allows us to make sense of everything else that we experience in this life.

Four, light is often associated with moral purity. God is perfectly good. He is the source and standard of moral purity. Those who want to connect to God need to come into the light. This is related to the previous point about truth. People who want to hide the truth and hide their wrongdoing hide in the dark. People who have nothing to hide walk in the light. Bringing wrong deeds into the light is a way to expose them and purify them. Louis Brandeis, the namesake of my alma mater, Brandeis University, and a Supreme Court Justice, once said, “Sunlight is said to be the best of disinfectants.”

So, God is glorious, beautiful, true, and good. He is the author and sustainer of life, the source of truth and beauty, and the source of goodness. And if we want to have a relationship with him, we must come out of the darkness and into the light. That’s what John means in verse 6: “If we say we have fellowship with him while we walk in darkness, we lie and do not practice the truth.” John says it is impossible to walk in the darkness and have fellowship with God. You can’t have a right, intimate relationship with God while walking in the dark. If you say that you can do both, you’re a liar and the truth isn’t in you.

What does it mean to walk in darkness? Perhaps we should let Jesus give us the answer. We all know John 3:16. But we don’t always pay attention to the verses that follow. Let’s read John 3:16–21:

16 “For God so loved the world, that he gave his only Son, that whoever believes in him should not perish but have eternal life. 17 For God did not send his Son into the world to condemn the world, but in order that the world might be saved through him. 18 Whoever believes in him is not condemned, but whoever does not believe is condemned already, because he has not believed in the name of the only Son of God. 19 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.”

According to Jesus, people who do evil things hide in the darkness. They refuse to come into the light. So, walking in darkness means living in ways contrary to God’s design and commandments. Walking in darkness means continuing to sin. Perhaps walking in darkness also means that the person in the dark hasn’t seen the truth yet.

John is probably correcting the false teaching that had invaded these churches. False teachers probably taught that it didn’t matter how people lived, as long as they had some knowledge of Jesus. But John says that if you have a relationship with light, you’ll walk in the light. God’s children are supposed to imitate their father. Consider the words of Paul in Ephesians 5:1–2: “Therefore be imitators of God, as beloved children. And walk in love, as Christ loved us and gave himself up for us, a fragrant offering and sacrifice to God.” God’s children are supposed to imitate God. Or, as Jesus put it, in John 8:12, “I am the light of the world. Whoever follows me will not walk in darkness, but will have the light of life.”

Now, at this point, it might be easy to think that Christians earn a relationship with God by not sinning. If we simply live rightly, we can have a relationship with God. If we start sinning again, we go back into the darkness and lose that relationship. In fact, if you look at verse 7, you might think that it is only after we live rightly for a while that Jesus’ death on the cross cleanses us from our sin. Verse 7 says, “But if we walk in the light, as he is in the light, we have fellowship with one another, and the blood of Jesus his Son cleanses us from all sin.”

But taking these verses to mean that we can we become clean in God’s eyes by our right living would be to take these verses out of context. In the next three verses, verses 8–10, John makes it clear that everyone has sin:

8 If we say we have no sin, we deceive ourselves, and the truth is not in us. If we confess our sins, he is faithful and just to forgive us our sins and to cleanse us from all unrighteousness. 10 If we say we have not sinned, we make him a liar, and his word is not in us.

John clearly says that everyone has a sin problem. If we don’t agree with that, we’re liars, because the truth is that we do have a sin problem. And if we claim that we don’t have a sin problem, we are calling God a liar, because God’s word, the Bible, clearly depicts our sin problem. A good chunk of the Old Testament is devoted to story after story that illustrates the pervasiveness of sin.

Before we continue, I don’t want to assume that we all understand what the word “sin” means. We tend to think of sin as a bad action, as a wrong deed. But sin is much more than that. I’ve been reading a book on Jesus’ death by a theologian named Fleming Rutledge. She writes,

To be in sin, biblically speaking, means something very much more consequential than wrongdoing; it means being catastrophically separated from the eternal love of God. It means to be on the other side of an impassible barrier of exclusion from God’s heavenly banquet. It means to be helplessly trapped inside one’s worst self, miserably aware of the chasm between the way we are and the way God intends us to be. It means the continuation of the reign of greed, cruelty, rapacity, and violence throughout the world.[3]

The origin of sin, really is when the first human beings turned from the God who is light and went to hide in the darkness (Gen. 3:1–13). When they did, the relationship between God and human beings was fractured and the power of sin was unleashed upon the world. God is light and he cannot mix with the darkness. But we chose darkness over light, and there are consequences for that choice. All of us begin life in the darkness.

Sin isn’t just that broken relationship. Sin is also a power. It’s “an infectious disease.”[4] It’s a heart problem that we can’t fix ourselves. In the Old Testament, the prophet Jeremiah said, “The sin of Judah is written with a pen of iron; with a point of diamond it is engraved on the tablet of their heart” (Jer. 17:1). In other words, the sin of those in Judah was written indelibly on their hearts. A few verses later, God says through Jeremiah:

The heart is deceitful above all things,
and desperately sick;
who can understand it? (Jer. 17:9)

This wasn’t just a problem for the people of Judah some 2,600 hundred years ago. This is a universal problem. Our diseased hearts produce disordered desires, and these desires lead to wrong actions. These desires are what end up making us dirty, or defiled. Jesus said, “But what comes out of the mouth proceeds from the heart, and this defiles a person. For out of the heart come evil thoughts, murder, adultery, sexual immorality, theft, false witness, slander” (Matt. 15:18–19).

We need to have a deep cleansing of this contamination within. Otherwise, we will remain in darkness and be separated from the God who is light. It’s not enough to shine light on our darkness. We need light to penetrate our dark interior lives.

This light cannot come through a better economy. If that were the case, Jesus would have come as a businessman or an economist. This light cannot come through mere education. Otherwise, Jesus would have been a professional philosopher or a professor. This light cannot come through better health. Otherwise, Jesus would have been a doctor, a nutritionist, or a personal trainer. This light cannot come through a better political system or environment. Otherwise, Jesus would have been a politician. The light cannot come through military conquest or violence. Otherwise, Jesus would have been a general.

No, what we need is a savior. We need someone will take care of our sin problem, not slap a band-aid on it. We need someone to take our sin and destroy it, and we need someone good who can make us good. We need someone who can clean us up and heal us. John tells us twice that Jesus is able to cleanse us. And he does that through his sacrifice on the cross. That’s what “his blood” refers to. In the Old Testament, a very clear idea emerges: sin demands punishment. It must be wiped out and destroyed. It is darkness and it cannot survive the blinding light of God. But in the Old Testament, God allowed his people to make sacrifices. Instead of the sinner being destroyed, the sinner could offer up a substitute, an animal, which would be killed. The life of the animal was substituted for the life of the sinner. The blood of the animal represents its life, which is sacrificed to atone for sin (Lev. 17:11).

When Jesus died, he was treated as a criminal. The cross was reserved the for the worst of Roman society. This is shocking: The man, Jesus of Nazareth, who is also God, died even though he was innocent. It took nothing less than the death of the Son of God to bring us out of the darkness and into the light. Fleming Rutledge has written, “There is something sickening in human nature, and it corresponds precisely to the sickening aspects of crucifixion. . . . The scandal, the outrage of the cross, is commensurate with the offense and the ubiquity of sin.”[5] That God would crush his Son for our sin should shock us, and it should show us the weight, the gravity, of sin.

When Jesus was on the cross, he absorbed our darkness so that we could enter into God’s light and not be consumed by it. He experienced the greatest darkness possible, the wrath of God. He was regarded as darkness and he was crushed so that God could punish our darkness without crushing us. Jesus’ light covers our darkness. Jesus’ blood covers our sin. It removes the otherwise indelible stain of sin. When God looks at those who are united to Jesus, he doesn’t see their sin, but instead he sees Jesus’ righteous, perfect, sinless life of light. He also sees Jesus’ sacrificial death in our place, paying the penalty for our sin. This was God the Father’s plan. It was also God the Son’s plan. That is, God the Father graciously gave his Son, and Jesus, the Son of God, graciously and willingly died for us. He endured all the darkness of the wrath of God so that we wouldn’t have to. He took on that darkness so that we could be children of light. As the apostle Paul wrote, “He has delivered us from the domain of darkness and transferred us to the kingdom of his beloved Son, in whom we have redemption, the forgiveness of sins” (Col. 1:13–14).

As I said last week, the only way to have eternal life is by having a relationship with Jesus. John makes that quite clear in this letter and also in his Gospel, his biography of Jesus. And when someone has a right relationship with Jesus, a number of things happen, things that God has joined together so that no man can separate.

First, there must be an awareness of the problem of sin. Without this awareness, we’re stuck in the dark. The irony is that those in the dark don’t think they’re in the dark, and those who have come to the light are more aware of their own darkness than ever before. It takes an act of God to bring us to the point of being aware of our own sin, being aware that it’s a real problem, because it’s rebellion against God, and being aware that we can’t fix this problem ourselves.

Second, we need to see that Jesus is our only hope. We need to see that he is the only one who can cover our sins.

Third, we must come to the light. We must come to Jesus, who is the light of the world and offers eternal life and light (John 8:12) But when we do that, we must confess our sins, and let them be exposed. We must tell God that we’re sinners, dominated by the power of sin.

Fourth, when we come to the light, God gives us the Holy Spirit. Really, he gives us the Spirit right at the moment of faith, right before we are even aware we have faith. Jesus said that one must be born of the Spirit before he or she can even see, much less enter, the kingdom of God (John 3:3–8). The Holy Spirit starts to cleanse us from the inside out. He gives us the power to walk in the light. He truly enlightens us. This doesn’t mean that we instantly stop sinning. Again, John assumes that we have a sin problem, one that remains to some extent even after we come to trust in Jesus. But that power is diminished because God transforms us. As Paul says, “if anyone is in Christ, he is a new creation” (2 Cor. 5:17). That means there should be a transformation in the way that we live.

Fifth, real Christians, those who have real, abiding faith and have been transformed by God, will walk in the light. John uses that metaphor, “to walk,” in the present tense, to suggest that this is an ongoing action. This isn’t something you did once when you heard a gospel presentation and made some kind of confession. Walking in the light is a day-to-day activity. Those who walk in the light won’t lead a secret life of sin. They won’t hide in the darkness, doing things that are not pleasing to God. Real Christians will start to obey God, and make a habit of obeying God, even if they fail at times. We should strive to live lives of integrity. That means we should live lives that are whole, that aren’t fractured into bits of the “holy” and the “profane,” or the “sacred” and the “secular.” The whole Christian life is a life of worship offered up to God in response to his great salvation.

So, in the end we can’t separate faith from obedience. We can’t separate faith from being transformed by God. Those who have real faith in Jesus also have the Holy Spirit, who enables us to change.

It would be easy to misunderstand what I’m saying and interpret this as, “We have to work harder to walk in the light.” But we need to see that this isn’t something that we do. Otherwise, our salvation would be our own. God saves us from start to finish. He enlightens us to see our true spiritual condition, which we can only see in the light of his own revelation of himself. He gives us the gift of faith. He gives us the gift of the Holy Spirit, and this is so that we can live as children of light, having a true, healthy relationship with the God of light.

We can see this grace in another passage in the New Testament, in Paul’s letter to Titus. In Titus 3:4–8, Paul writes,

But when the goodness and loving kindness of God our Savior appeared, he saved us, not because of works done by us in righteousness, but according to his own mercy, by the washing of regeneration and renewal of the Holy Spirit, whom he poured out on us richly through Jesus Christ our Savior, so that being justified by his grace we might become heirs according to the hope of eternal life. The saying is trustworthy, and I want you to insist on these things, so that those who have believed in God may be careful to devote themselves to good works. These things are excellent and profitable for people.

God brings us into the light, not by our good works, but because of his mercy. He washes us by regenerating us. That means he makes us into new creatures. He causes us to be born again. And he reconciles us to himself, so that we are justified, or declared innocent and right, in his eyes. We can then have the promise of eternal life. And this is intended to cause us to live lives of good works, lives lived in the light, where we have nothing to hide from God or anyone else. So, we’re not saved by good works. But our salvation leads to good works. In other words, good works don’t cause our salvation, but our salvation causes good works.

People of all backgrounds have received this mercy and grace. Even the worst of sinners have been brought into the light. Consider one more passage from Paul, this time 1 Cor. 6:9–11:

Or do you not know that the unrighteous will not inherit the kingdom of God? Do not be deceived: neither the sexually immoral, nor idolaters, nor adulterers, nor men who practice homosexuality, 10 nor thieves, nor the greedy, nor drunkards, nor revilers, nor swindlers will inherit the kingdom of God. 11 And such were some of you. But you were washed, you were sanctified, you were justified in the name of the Lord Jesus Christ and by the Spirit of our God.

That passage shows that those who remain in the darkness will not inherit the kingdom of God. Frankly, all of us have been idolatrous, greedy, and revilers of some kind or another. I’m sure most of us have been sexually immoral, for even lust is a form of sexual immorality. But consider what Paul says: “Such were some of you. But you were washed, you were sanctified, you were justified in the name of the Lord Jesus Christ and by the Spirit of our God.” And Paul encourages them, too, to walk in the light.

Before closing, I want to give us some very practical ways to respond to this passage.

If you’re here today and you haven’t truly entered into the light, whether you’ve never confessed your sin to God or whether you’ve been faking it, living a life that doesn’t line up with God’s design for our lives, I would urge you to come to the light. The only way to be known as the person you truly are is to enter into the light. I think we all want to be known and loved by others for who we truly are. We want people to see the real us and not reject us. If you let the light expose who you truly are, if you confess your sins to God and seek forgiveness, he will accept you. And he can do that because of what Jesus has done for us.

I think one of the reasons why people are miserable is because of guilt. They have done things that they don’t feel can be forgiven. Shakespeare’s play, Macbeth, is an example of this. Lady Macbeth pushes her husband, Macbeth, to kill Duncan, the King of Scotland. After Macbeth kills Duncan, he feels a guilt that he thinks can never be removed. He says,

Will all great Neptune’s ocean wash this blood
Clean from my hand? No, this my hand will rather
The multitudinous seas incarnadine [make red],
Making the green one red.[6]

His wife, Lady Macbeth, says, “A little water clears us of this deed.”[7] But, later in the play, she struggles with guilt. She sleepwalks and she imagines that Duncan’s blood has permanently stained her hands. So, she scrubs and scrubs them. She famously says, “Out, damned spot! Out, I say!”[8] She asks, “What, will these hands ne’er be clean?”[9] Our guilt will remain unless we are cleansed by Jesus. He is the only one who can wash that damned spot off of us.

But in order to be a Christian, you must acknowledge your sin problem. You must realize that you have been living in rebellion against God because you haven’t pursued a relationship with him. You’ve been hiding from him. And if you don’t think you have a sin problem, remember, you’re calling God a liar, and that is rebellion. It is time to agree with God. You must also realize that having a relationship with Jesus is the only way to be reconciled to God. Come into the light. Let your sin be exposed. Confess it to God. He already knows. Remember that Jesus can cleanse us from all sin and all unrighteousness. And if you come to Jesus, you can live a new life of following him. You can walk in the light. You can keep Jesus’ commandments.

If you’re a Christian, continue to walk in the light. We shouldn’t live secret lives of darkness. Sometimes, we walk a portion of our lives in the light and little bits of our lives in the darkness, doing things we know we shouldn’t. We all have struggles against sin. One way to walk in the light is to confess sins to each other. We should certainly confess things to people when we’ve hurt them or betrayed them in any way. But it’s helpful to also confess our sins to those who aren’t involved. That way, we can invite people into our lives who can help us. They can pray for us. They can hold us accountable.

Sometimes, it’s best to find just one or perhaps a few Christians you trust to hold you accountable. Let your weaknesses be known. Ask them to check in on you. Ask a trusted person to pray for you. Don’t hide in the darkness. That’s where we’re truly at our weakest and most vulnerable.

And, finally, as a church, we need to consider this: To have real relationships with each other, we must first walk in the light. Look at the beginning of verse 7: “But if we walk in the light, as he is in the light, we have fellowship with one another.” In verse 3, John says he is writing so that his readers can have true fellowship, true communion, with the apostles, for they have true fellowship with God. In other words, to have a true relationship with God, you must embrace the apostles’ message. But in order to have true relationships with each other, we must walk in the light. You can’t have a deep, lasting relationship with someone apart from first having a right relationship with God. And, beyond that, we can’t have real relationships with each other if we’re hiding our true selves.

We tend to wear masks on in public. We may be struggling with sin, or struggling emotionally, and yet when someone asks how we are, we say, “Oh, I’m fine.” We say that when we’re anything but fine. Let’s take off our masks. Let other people know the real you. Don’t hide in the dark. The light is the safest place for us to be. And it’s also the most liberating place for us. It’s the place where we find real life and real joy.


  1. Unless otherwise noted, all Scripture quotations are taken from the English Standard Version (ESV).
  2. C. S. Lewis, “Is Theology Poetry?” in The Weight of Glory and Other Addresses (New York: HarperCollins, 2001), 140.
  3. Fleming Rutledge, The Crucifixion: Understanding the Death of Christ (Grand Rapids, MI: Eerdmans, 2015), 174.
  4. Ibid., 190.
  5. Ibid., 197.
  6. William Shakespeare, Macbeth, II.ii.63–66.
  7. Ibid., II.ii.70.
  8. Ibid., V.i.35.
  9. Ibid., V.i.43.