Jesus taught that sexual purity goes far deeper than avoiding adultery. In the Sermon on the Mount, he said that looking at someone lustfully is already adultery in the heart. Lust treats people as objects, and sexual sin follows a predictable path from our eyes to our thoughts to our actions. The Jesus way is to deal radically with temptation and retrain our hearts to desire what honors God.
Lust Is Adultery Below the Surface
In Matthew 5, Jesus made six contrasts between the common understanding of God’s law and its true intent. The first was about murder and anger. The second applied the same principle to adultery and lust. In today’s hypersexual culture, his teaching is more relevant than ever, and none of us can afford to take it for granted.
Jesus began by quoting one of the Ten Commandments, then pointed to the heart behind it.
Matthew 5:27-28 You have heard that it was said, ‘You shall not commit adultery.’ But I tell you that anyone who looks at a woman lustfully has already committed adultery with her in his heart.
Jesus didn’t lower the standard. He raised it. The physical act of adultery is only the visible expression of something deeper. Lust treats people as objects, a means to satisfy a desire rather than people made in God’s image. Pornography is a clear example, reducing a living person to an image with a single selfish purpose. And while Jesus spoke about men looking at women, lust is a temptation for everyone.
Sexual Sin Follows a Predictable Path
Sexual sin rarely comes out of nowhere. It usually begins with what we see, moves into what we think about, and eventually shows up in what we do. Job understood the importance of guarding his eyes.
Job 31:1 I made a covenant with my eyes not to look lustfully at a young woman.
Once the eyes linger, the heart engages. We start entertaining the image, turning it over in our minds and feeding the desire. That’s why Proverbs says, “Above all else, guard your heart” (Proverbs 4:23). James describes where this path leads: desire “gives birth to sin; and sin, when it is full-grown, gives birth to death” (James 1:15). Jesus wants us to understand where our actions are born so we can stop them before they grow.
Deal Radically With Temptation
What’s the answer to the heart problem of lust? Jesus used shocking language to show how seriously we should take it.
Matthew 5:29-30 If your right eye causes you to stumble, gouge it out and throw it away. It is better for you to lose one part of your body than for your whole body to be thrown into hell. And if your right hand causes you to stumble, cut it off and throw it away. It is better for you to lose one part of your body than for your whole body to go into hell.
Jesus was exaggerating to make a point, not calling for self-harm. After all, a person can still lust without an eye or a hand. His point is that sexual purity is worth enormous sacrifice, and it can’t be achieved with half-measures. If you’re losing the battle, cut off the triggers. That might mean deleting certain apps, changing what you watch, installing accountability software, or avoiding situations that lead you into temptation.
Retrain Your Heart
Removing temptation is only half the battle. True purity also requires new thoughts and new desires. Paul described the mindset of someone who belongs to Jesus.
Colossians 3:1-2 Since, then, you have been raised with Christ, set your hearts on things above, where Christ is, seated at the right hand of God. Set your minds on things above, not on earthly things.
We retrain our hearts by filling our minds with God’s Word, relying on his Spirit through prayer and worship, and leaning on other believers for encouragement and accountability. Paul promised, “Walk by the Spirit, and you will not gratify the desires of the flesh” (Galatians 5:16). And if you’ve already fallen, Jesus offers forgiveness and a fresh start.
The Takeaway
What did Jesus teach about lust and sexual purity? He said lust is adultery of the heart. The Jesus way is to guard your eyes, deal radically with temptation, and retrain your heart to love what God loves.
