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The Battle for Sexual Purity

July 18, 2021 Speaker: Kit Johnson Series: Sermon on the Mount

Topic: Expository Passage: Matthew 5:27–30


(Read Text) This passage has to be one of the most counter-cultural passages in all of Scripture. I say this, we are not merely a society that tolerates every type of sexual perversion; instead, we glory in every type sexual gratification as praiseworthy.

This past winter, I read, The Rise and Triumph of the Modern Self, by Carl Trueman, and he includes a stunning quotation by Sigmund Freud that sums up the spirit our society. Freud is speaking of moral evolution he believes that mankind has experienced and says, “Man’s discovery that sexual love afforded him the strongest experiences of satisfaction and in fact provided him with the prototype of all happiness, must have suggested to him that he should continue to seek the satisfaction of happiness in his life along the path of sexual relations and that he should make…erotism the central point of his life” (Quoted by Trueman on p. 205).

That is a jaw-dropping quote that is hard to fathom. Freud says that we should make sexual gratification “the central point” of our lives. And Trueman demonstrates that Freud’s values have won the day in Western culture.

So, our culture believes that gratifying every sexual impulse is not just okay; it is praiseworthy. And we see this in the sexualization of our media, advertisements, etc. Sex is everywhere, and we are constantly being told that it is the key to happiness.

But everything going on out there isn’t even my biggest problem. My biggest problem is inside here. Our hearts are wicked, and the lust of the flesh is driving force in all of us. And because of the influence out there and inside here, we often become experts at downplaying lust and whatever sins arise from it.

But in our text, Jesus stands up to Freud, Western cultural, and the deceitfulness of our hearts, and he says that lust has no place in the heart of a Christian. We must not excuse it or tolerate it. Instead, we must eradicate lust and every other sexual expression outside God’s design. So, this is a hard text, but I hope that we will listen to what our Lord says as both our authority and our loving Savior, who always knows what’s best. Notice first…

I.  Jesus demands marital faithfulness (v. 27).

Remember that the previous paragraph began by quoting the 6th Commandment, “You shall not murder.” Jesus begins this paragraph by quoting the 7th commandment, “You shall not commit adultery.”

This command is pretty straightforward. Way back in Genesis 2:24, God declared his intention for marriage, “Therefore a man shall leave his father and mother and be joined to his wife, and they shall become one flesh.” In other words, they belong to each other in every sense. They are “one flesh.”

And Scripture teaches that God designed the sexual relationship exclusively for this context. In fact, Hebrews 13:4 goes so far as to refer to the sexual relationship as the “marriage bed.” That’s exclusively what God made it for.

And he made this relationship between a husband and a wife to last for a lifetime. Jesus declared in Matthew 19:6, “Therefore what God has joined together, let not man separate.” So, marriage is not just self-serving contract between two people, as our culture believes; instead, God joins a husband and wife together, and he declares that we must not destroy what he has created.

When you take all of this into account, it’s easy to see why God chose adultery as one of the sins to confront in the 10 Commandments. It is a violent attack on marriage—one of God’s first creations and one of the most foundational institutions he designed for human flourishing.

Now, I recognize that our society believes it has moved past such an “oppressive” command as the 7th We believe, “All you need is love,” as if self-serving passion is superior to the sacrificial love that is the foundation of biblical marriage. We also believe, “If it makes you happy, it can’t be that bad.” We have made immediate happiness the end of all things, which, ironically, in the long run produces more sadness than happiness.

It’s fascinated how many secular studies have demonstrated that God’s design for marriage and family produces so much more joy in the long run.

But Satan is a master of deceiving us to believe, “I am the exception.” I’ve heard professing believers say things like, “I’m not happy in my marriage, and God wouldn’t want me to be unhappy. So, I’m sure he would want me to enjoy this affair.” It’s absurd, but it happens all the time.

And just because it sounds absurd today, doesn’t mean you are above believing it someday. Plenty of Christians have thought, “I would never think that.” But in a time of weakness, Satan strikes with stunning effectiveness.

Therefore, even if no one in this room is even contemplating adultery, I must say in the clearest terms possible that God condemns it without exception. Don’t ever let your mind even begin down that destructive path.

Proverbs 5:3–5 warn, “For the lips of an immoral woman drip honey, and her mouth is smoother than oil; but in the end she is bitter as wormwood, sharp as a two-edged sword. Her feet go down to death, her steps lay hold of hell.” And Proverbs 7:24–27 warn, “Do not let your heart turn aside to her ways, do not stray into her paths; for she has cast down many wounded, and all who were slain by her were strong men. Her house is the way to hell, descending to the chambers of death.”

These warning and others in Proverbs 5–7 are so good, because they account for the deceptiveness of immorality and adultery. Solomon warns that most people who get trapped in sin don’t set out to ruin their lives. But our hearts are terribly deceitful. Therefore, do not presume on your marriage. Guard your heart and guard your purity. Then your marriage, because it is a good gift of God, and sin will never deliver something better than God’s good will.

And if you have tried to pursue a healthy marriage, but no matter what you do, you are stuck in a difficult marriage, then trust that God is enough. That person who flatters you and seems to promise so much happiness is not worth sacrificing your marriage or especially the nearness of God. Stay faithful to God’s design and trust his grace to sustain you.

So, Jesus begins by affirming the 7th God demands marital faithfulness. But v. 28 is where Jesus really turns up the heat. Notice that…

II.  Jesus demands purity of heart (v. 28).

This is one of those verses that hits us like a ton of bricks. “Jesus demands what?” I imagine that it had a similar impact on Jesus’ original audience, when he first preached the Sermon, because Jesus demands a lot.

But v. 28 shouldn’t be that surprising, because all Jesus does is draw out an implication of the 7th and 10th Commandments. The 10th Commandment stated, “You shall not covet your neighbor’s house; you shall not covet your neighbor’s wife, nor his male servant, nor his female servant, nor his ox, nor his donkey, nor anything that is your neighbor’s” (Ex 20:17).

Lust and coveting are essentially synonymous. They both refer to a strong desire to have something which God has not given me. At their core, they both declare that God has not given me what is good; therefore, I want the object of desire more than I want God.

And covetousness also violates love of neighbor, because it prioritizes my gratification over his good. BTW, this always applies to sexual lust. Lust is never about sacrificially loving another person; rather, it turns a person into an object for my pleasure.

So, v. 28 mostly is drawing out an implication of the 7th and 10th God had already said that it is wrong to desire another man’s wife, and by implication another woman’s husband.

But Jesus goes even further by saying that lust directed toward any woman (or man), whether married or not, is a serious sin on the level of adultery. It’s important that we take a moment to clearly understand what Jesus is and is not condemning.

Meaning of Lust: First…

Jesus does not condemn all physical attraction. This one is important, because it would be easy to think that the solution to Jesus’ demand is to squash all physical desire. But that’s not what the Bible teaches.

Instead, Proverbs 5:15–19 teach that a husband and wife should enjoy each other physically and sexually. It also teaches that this pleasure is an important way to promote a loving and healthy marriage and protect each other from wandering passions.

Furthermore, Song of Solomon celebrates the physical attraction between a couple anticipating marriage. So, if you are single, you shouldn’t feel guilty about being attracted to the physical beauty of someone of the opposite sex. God wants you to be attracted to your future spouse. Second…

Jesus does not condemn an innocent sight or the temptation to lust. Sometimes we see things that we don’t expect to see or want to see. That’s not sin. As well, it’s not a sin to be tempted to look at something.

That’s not to say that we shouldn’t work to eliminate temptation or to change our desires so that certain temptations don’t hit us so hard. That’s an important topic for another day. But for now, I simply want to note this is not what Jesus has in mind. Rather…

Jesus condemns prolonged and intentional covetousness. I included the adjectives, because the verb translated “lust” is in the present tense, and in this particular context, it speaks of a prolonged gaze. So, Jesus is not condemning the guy or girl in the store who accidentally sees something he or she doesn’t want to see.

No, he is speaking of someone who sees something forbidden but continues to gaze on it with a lust to have it or out of the selfish pleasure the gaze brings. Jesus says that this lust of the eyes is wicked and ungodly.

Jesus condemns self-indulgent passions and imaginations. Notice that this gaze penetrates to the heart. In fact, Jesus says he “has already committed adultery with her in his heart.” So, it’s not just the look that Jesus condemns; he condemns the passions and imaginations that accompany the look. Jesus says there is no place in the heart of a Christian for arousing and indulging sexual passions outside God’s clearly defined parameters.

So, this is a good spot to mention that this means that dating couples should not kiss our touch each other in a way that arouses these kinds of passions in each other. Many people like to believe that anything goes as long as you don’t cross the line of immorality.

That’s absurd. Anything that arouses passions that you cannot fulfill biblically is driving you into lust. If we are going to take Jesus seriously, we must eliminate anything that triggers lust. We must not buy the idea that we’re okay as long as we aren’t immoral. That’s the height of legalism.

Now, I recognize that what I am saying is way out of bounds with the culture, and even with a lot of Christianity. But your argument is not with me but with Jesus. Sexual lust has no place in the heart of a Christian. And Jesus drives this point home when he describes…

The Severity of Lust: Jesus’ condemnation is incredible. He says the one who lusts “has already committed adultery…in his heart.” Again, considering how strongly the Bible condemns adultery, that is a huge statement.

Now, I do not believe Jesus is saying that the two are literally equivalent in God’s eyes. Other passages speak of immorality and adultery in very strong language, and they bring severe judgment from God. We’ll talk about that more next week with vv. 31–32.

But at the very least Jesus is saying that lust reflects the same adulterous heart. When a man or a woman craves someone in a way that they should only crave their husband or wife, it is a wicked sin before God, even if they never act on the craving. This is because in some sense, he or she has given a portion of the heart to something that God has forbidden.

Again, this is seriously out of line with our culture. Last summer I came across a document from the New York health department that was intended to help people deal with the lack of sexual encounters during COVID restrictions. It actually encouraged people to use pornography as a safe alternative. It’s not uncommon for married media personalities to talk openly about their lust for someone other than their spouse. Instead, it’s assumed to be normal and perfectly acceptable. People talk all the time about “enjoying the scenery” at the beach or other places.

But Jesus said in v. 6, “Blessed are those who hunger and thirst for righteousness.” If that’s me, then I must hate all that junk. I should hate pornography, I should hate every temptation to lust, and I should work to view others not as objects of my pleasure but as people made in the image of God who deserve real sacrificial love.

God doesn’t just demand purity of action; he demands purity of heart. In light of Jesus’ high demand, Jesus’ 3rd demand is…

III.  Jesus demands an aggressive pursuit of holiness (vv. 29–30).

Again, Cheryl Crow would tell you, “If it makes you happy, it can’t be that bad.” But Jesus does not agree. He warns that…

The stakes are high. Notice that both vv. 29, 30 conclude by assuming that when you toy with lust you put you eternal destiny at risk. Twice, Jesus warns, if you toy with lust, you risk “your whole body (being) cast into hell.”

Why would he say such a thing? He’s not saying that a true believer can lose his salvation, because in other places he says this is impossible. But he is saying that lust and adultery are so contrary to the nature of the new birth that these sins cannot continue unchecked in the heart of a true Christian.

1 Corinthians 6:9–10 state, “Do you not know that the unrighteous will not inherit the kingdom of God? Do not be deceived.Neither fornicators, nor idolaters, nor adulterers, nor homosexuals, norsodomites…will inherit the kingdom of God.” Again, these sins are fundamentally opposed to the new birth. And when someone gets saved, the gospel invades their territory.

Verse 11 adds, “And such weresome of you. But you were washed, but you were sanctified, but you were justified in the name of the Lord Jesus and by the Spirit of our God.” Again, the gospel changes these things.

And Jesus says that this extends even to our heart’s desires. You cannot “hunger and thirst for righteousness” while hungering and thirsting after sexual perversion. If you choose the latter, you risk “your whole body (being cast into hell.”

Now, does this mean that true Christians can’t commit adultery or endure serious struggles with heart purity? Of course not. Sadly, many true believers have committed serious sins or have endured long struggles against deeply imbedded habits. But the key is that they hate their sin, and they want out.

Therefore, if you aren’t there, and you are trying everything in your power to justify thoughts, passions, or actions that God condemns, then I really hope the Holy Spirit is tearing your heart to shreds right now. And because I love you, I pray he will make you miserable until you repent.

Lust, pornography, and sexual sins are nothing to toy with. Heaven and hell are at stake, your family is at stake, and your joy is at stake. So, repent today. And then follow your repentance by understanding that…

The stakes require radical amputation. Verses 29–30 are intended to be shocking. In the ancient world the right eye and the right hand were considered strong and essential body parts. Imagine how lost a soldier would be without his right eye to aim or his right arm to fight. It’s a huge loss! So, Jesus is making a big claim.

Now, Jesus is not calling us to literally gouge out our eyes, cut off our arms, or anything like that. Back in 2006, a student at Crown College in Knoxville, TN took this command so far that he burned down an adult book and video store. He got in big trouble, and what he missed is the fact that external actions alone can’t change the heart. If you are a pervert, gouging out your eye won’t fix it.

But while that’s true, Jesus is saying that we must be willing to take radical steps to guard our hearts. For example, if you can’t control it, you might need to throw away your phone, computer, or TV, or only use them around other people. There may be a time, when you have to consider quitting a job, changing your route to work, or your daily schedule. If you are dating, and you love that person, you better have very clear safeguards in place to protect both of you.

Now, you may hear all of that and have 100 excuses as to why those things are legalistic and absurd. And in certain cases, they may be. But if your soul, your family, and your gospel witness are at stake, they are a small price to pay for holiness, nearness to God, and the protection of others.

Let’s all feel the urgency in Jesus’ voice and respond accordingly. To close our time, I’d like to call you to take 4 practical steps to guard and promote purity.

Build resistance through the disciplines of grace. “How can a young man keep his way pure? By keeping it according to Your word…Your word I have treasured in my heart, that I may not sin against You” (Ps 119:9, 11).

Very often, the best defense is a good offense. If you are in the Word and in prayer, your happily engaged in the life of the church, and your living a disciplined Christian life, there are simply less cracks for Satan to exploit. It’s like your body. The healthier you are, the harder it is for a virus to take over. You’re better off pursuing good health than you are always fighting infection.

You may think that singing about God’s sovereignty has nothing to do with fighting lust, but it does. Live a healthy life in reliance on God’s grace, and you will build resistance to Satan’s temptations.

Build obstacles to failure. If you are struggling with sexual temptation or any other sin, you really need to take some time to identify patterns to your struggle. Is there a certain time of day when your struggle is especially strong? Maybe a certain television show, style of music, location, or person arouses your flesh in unusual ways.

Once you have identified those patterns, build obstacles which prevent those patterns from repeating themselves. And Jesus says, don’t be afraid to take seemingly radical steps. I don’t care how much you spent on that iPhone, it’s not worth more than your soul.

Another important obstacle is accountability. The Christian life is too hard to do it alone. Find someone that will ask you the tough questions and challenge you to do better. Let them share the struggle with you.

Replace sinful patterns and habits. Ephesians 4:22–32 teaches that an important part of putting off sin is putting on something positive to replace it. Otherwise, you are simply creating a void that something will fill. BTW, it doesn’t have to be something spiritual. Exercise, pick up a productive hobby, get out with godly friends, but don’t just sit there and stare at the sin that you left behind.

Deal with failure biblically. The question is not if you will fail but how you will respond when you do. Confess it, rest in God’s promise to forgive, learn from your failure, and try again with the confidence that God’s grace is sufficient.


Finally, I hope you know that you are not alone. You are surrounded by sinners who have all fallen in our own ways. And every mature believer knows that I only am what I am by the grace of God. So, if you are struggling get help. I would love to talk with you, pray with you, and come up with a battle plan. Don’t worry about being ashamed. I’ve seen enough that you will not surprise me. Even if it’s scary, nothing is more important than being right with God. So, let’s help each onto glory.

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