Summary: Jesus internalizes the seventh commandment to not commit adultery in our hearts through lust. Lust is a cancer to our relationship with Jesus and our spouse. We must keep our covenantal commitments.
In my lust post, I talked about the core issue of anger that causes murder in our hearts. In this post, I want to address the next part of Jesus’s Sermon on the Mount, adultery and lust.
Not everyone struggles with adultery. Single people don’t struggle with adultery. Or do they? Anyone can struggle with adultery the way Jesus defines it. The commandment on adultery leaves wiggle room for the sin of lust. That’s something everyone struggles with.
We can follow the Ten Commandments so strictly that many of us can say we have not broken them. But Jesus internalizes these commandments in His Sermon on the Mount to make it hard to say we have followed any of them. So, let’s look at adultery and lust to see how Jesus teaches us about our wayward hearts.
Keeping the Commandment
The seventh commandment simply states, “You must not commit adultery” (Exodus 20:14). Adultery is cheating on your spouse. This commandment seems cut and dried. It is also a very specific command that only applies to married couples.
A single person would only be able to commit adultery if they are in a committed relationship, say, have a fiancé. Otherwise, they are not committed to one person. Adultery comes to the deeper issue of a person’s character. Are they the kind of person with a wayward heart that chases after every temptation they see?
If, like the Pharisees in Jesus’s day, you define the commandment so specifically that is impossible to violate it unless you literally cheat by having sexual relation with a member of the opposite gender who is not your spouse, it’s extremely different to violate this commandment.
Following the letter of the law, you could get away with fantasizing about another person then your spouse, dreaming about committing the act of adultery without physically doing it, or even looking at a member of the opposite gender without making any advancements. You could even start a relationship with that person and not commit adultery.
You can only violate the old covenant laws if someone you in the act of adultery. Otherwise, you could get away with a lot of behavioral gestures that weren’t technically adultery. There was much freedom and wiggle room in these laws.
But if you follow the spirit of the laws, it’s much more difficult to get off scott free. The spirit of the law takes into account the matter of the heart. It calls us to examine ourselves for even the intent that we want to violate the law. It considers temptation, character, and our integrity.
So, depending on how honest we are with ourselves, we could interpret the laws literally or follow the spirit of the law. If we had no integrity, we could decide on a case-by-case basis whether to follow a law literally or by the spirit of that law. But Jesus leaves no room for us to do this.
Lust in the Heart (Matthew 5:27-30)
During His Sermon on the Mount, Jesus takes up the matter of this seventh commandment. We see Jesus dealing with the law, the Ten Commandments, by saying, “You have heard it was said” followed by the commandment He addresses.
These dealings with the commandments follow His teaching that He has come not to abolish the law but to fulfill it (Matthew 5:17-20). Through His teachings, Jesus calls us to obey the law by obeying Him. His disciples follow the old covenant law by following Him. Obedience to Jesus means fulfillment of the old covenant laws.
Jesus brilliantly forces us to follow the spirit of the laws and commandments by internalizing each of them in His sermon. After quoting the seventh commandment about adultery, Jesus says, “But I say to you.” Following Jesus’s teaching on the law about adultery, we must consider our attitude and thoughts instead of our outward actions.
We cannot get away from our thoughts. The Holy Spirit dwells in us and monitors our thoughts. He lets us know when we have violated our covenant relationship with Jesus. But He also provides forgiveness and cleansing to us when we violate Jesus’s teachings in our thoughts and heart.
Adultery is the outward act of a sinful, wayward heart. We can no longer get away with even looking at the opposite gender with lust. But it’s hard for many to define lust. In my spiritual formation class at Bible College, my professor said to define it by explaining it as, “Taking a long second look at the opposite gender.”
He was trying to show that we cannot help our original thought when we look at someone. But if we go back for a long second look, taking in the figure of the opposite gender, we are lusting after the flesh. One student in the back of the room with his head down, whom we all thought was asleep, raised his hand and said, “That’s why you take a good long first look.” Even our professor could not avoid smiling at this comment.
This illustrates the difficulty we have with lust. While we may not act on lust and commit adultery, we can lust with our eyes, hearts, and minds. The spirit of the law shows us a mirror into our hearts. It shows our desire and commitment to the temptation before us. Without the Holy Spirit’s conviction, we can get away with violating this commandment even though we don’t physically commit adultery.
Our spouse knows us well. They can tell our wayward heart by looking into our eyes. In a crowded restaurant, we may think we got away with it. But they see when we look away from them. Then notice when we look at the opposite gender in the room.
Adultery of the heart and eyes puts little knife cuts into our relationship with our spouse. They notice they are no longer in our view. I wayward eyes betray our wayward heart. It looks for a diversion of our attention from them to a stranger. Our commitment to hold them first and only in our hearts goes by the wayside.
We violate our commitment made in our vows. It hurts them even if they don’t show it or speak it. Part of the human condition is a heart divided. Temptation spoils the commitments we make. We cannot get away from the divisions sin has caused in us.
The original commandment deals with adultery in a committed relationship. But even singles not in a relationship can’t get away from lust. Anyone can commit this sin of lust. Every disciple of Jesus gives allegiance to Jesus alone. Lusting after the opposite gender makes them an idle. So, anyone who commits lust in their heart violates a committed relationship to Jesus and their spouse.
We may not define lust well, but we know when we’ve committed it. It starts with looking at the opposite gender. Our brain records everything we look at. Lust happens when we play that image over and over in our mind. We think about what we would do with that person. Then we no longer think of the person as a person, but as an object. By objectifying the image we gathered with our eyes, we depersonalize them so we can commit lustful and sinful acts in our minds. We no longer care that this is a person.
That’s what lust ultimately does. It takes away the personhood of individuals and turns them into objects of lust. We can do whatever we want with a depersonalized image. We no longer care they are a person with feelings, thoughts, commitments, and possible relationships. We violate the image of the person, and therefore violate the personhood of that person. We take away their identity so we can do what we want with their image.
God doesn’t allow us to get away with lust. He made that person in His image. And we must not violate the image of God and others. That’s the sin behind the sin of lust and adultery. That’s why Jesus won’t let us get away with it. We may not literally violate the seventh commandment, but we violate the spirit of this law through lust.
We must deal with our wayward hearts and eyes. Like Job, we must make a covenant with our eyes not to look with lust on the opposite gender (Job 31:1). When we make a commitment with wedding vows, we must not break it. How would you like for someone to lust after you? To violate our identity and personhood? Then we must not do that to others. We must control
Lust Is a Cancer
Cancer is a malady of cells in our body. It robs us of years of life. It robs us of happiness, health, and joy. When people hear the word cancer, there are no joyful reactions to it. In the same way we view cancer, when interview lust and adultery. Lust destroys the committed relationship we are in with our spouse and the Lord.
Looking after another is the same as taking an idol against the Lord. The prophets place our relationship with the Lord as it comes in the relationship like marriage. Jeremiah is especially prolific in talking about this relationship. He talks about idolatry like spiritual adultery. God views himself as our husband.
Lust violates the covenant we make with our spouses, or for single people the covenant they had made with the Lord. It feeds on our committed relationships like a cancer. It lets our spouse know we are searching for someone else. It puts a wedge between us.
That’s why Jesus says anyone who lusts after another has committed adultery in their heart (Matthew 5:28). Just because Jesus speaks to men about their lust does not mean only men do it. Women do it as well. We are all guilty of lust. Because lust is behind adultery, Jesus says we can commit adultery without performing the physical act. All it takes is a thought. That’s why we must take our thoughts captive to Christ (2 Corinthians 10:5).
Just as surgeons cut cancer out of our bodies, Jesus tells us to tear out the I that causes us to sin and to fight off our right-hand if it causes us to sin. It’s better to lose a body part than to lose our souls forever in hell. We must think of lust the same way we think of adultery. Both are damaging to our souls.
When we make a commitment, integrity demands we keep that commitment. Jesus expects it of us, and so does our spouse if we are married. We are in a committed relationship and no temptation of the opposite spouse should draw our eyes away from our commitment. We cannot hurt so deeply the person you love.
Don’t Risk Your Soul
Jesus helps us realize how lust can destroy our souls. It doesn’t only hurt our committed to an end partner. It hurts us. It places us in peril as we commit sin against our spouse and the Lord. The Bible still talks about Jesus in the New Testament as our bridegroom.
So, we must not take lust so lightly. It can disqualify us like any other sin from our eternal inheritance in heaven. Let us make the commitment not only to love our spouse and Jesus, but to not commit lust in our hearts, adultery against our committed relationships, for the sake of our souls, if not our relationships. Your soul is not worth a fleeting glance.
Pledge your integrity and allegiance to Jesus and your spouse (if you have one) that you will not allow your wandering eyes to latch onto and violate the personhood of the opposite gender. Follow through with your commitment and hold your relationship with Jesus and your spouse in the highest of regard.
Now that we have discussed lust and adultery, I want to move next to the related topic of divorce and marriage.