We’re looking at how Deuteronomy takes the commandment “do not commit adultery” and works it through into society. It’s a command we still need to hear.
A 2015 YouGov survey in the UK found that 1 in 5 married people would admit to having had an affair. The reasons were a mixture of flattery (an external force), and emotional and physical dissatisfaction (internal force).
We’re going to look at what Deuteronomy has to say to expand on “do not commit adultery”, how Jesus applies it more deeply for us, and then take a look at some practical outcomes.
Whether you’re married, widowed, or single, you’ll see how this command opens your heart before God.
This is a profoundly spiritual issue for everyone.
These notes accompany a sermon on YouTube delivered at Bromborough Evangelical Church in April 2025. You can find more in the series in our sermon index.
Beware the spiritual dangers
We can take the command “do not commit adultery” and try to work it into a positive statement: Remain in joyful, faithful, committed love.
Deuteronomy 22:13-30 lists various case laws to do with adultery, each of which has an absence of joyful, faithful, committed love. The verses deal with cases of obvious adultery (which results in death for both the man and the woman), plus some more tricky situations (like a man with an engaged woman). The laws protect the innocent and vulnerable (rape). In each case, the wilful act of adultery is a cause for death.
That need to protect the vulnerable runs right through Deuteronomy like a watermark. It comes up again in Deut 24.
The Divorce Law
Read Deut 24:1.
It’s not clear what “something indecent about her” might mean, but the man is able to send her away. Giving her a certificate of divorce protects her. If she enters into another marriage, she can’t be accused of adultery because she has her certificate. If her second husband divorces her or dies, she can’t go back to the first husband. Again, she’s protected from men passing her around.
Those are the only laws on divorce in the Old Testament.
By Jesus’ day, people were still puzzling over what grounds there might be for divorce: What was “something indecent”?
Read Matthew 19:3-6.
The Pharisees were asking him about Deut 24. But Jesus took them back to first principles in Gen 1 & 2. It’s a brilliant step that applies to all questions of sexual ethics, including LGBT issues. When a man and a woman marry, they become one flesh. They are one. It’s a spiritual union, applied to all humanity.
And here’s the thing: If God has joined two people into one, what wickedness must happen for that union to be broken?
But the Pharisees weren’t done. Read Matthew 19:7-9.
- Notice the words: “Why did Moses command…” vs “Moses permitted…”
- Essentially, since you were going to abuse and divorce women anyway, God gave you laws to protect them.
- The root of the problem was the desire to divorce: And that came from hard hearts. Hearts of unforgiveness towards their wives. Or hearts that would rather trade a wife in for a better cook, or for a younger, prettier model. Hearts – it must be pointed out – nothing at all like God’s heart for you.
A desire for easy divorce is fuelled by the twin forces of a heart hardened against God, and a heart hardened against others. A desire for easy divorce is a spiritual disaster.
Spiritual disaster
To see more of why, we need to listen to more of Jesus: Read Matthew 5:27-30.
Two people don’t just meet and immediately decide to have an affair outside marriage. It begins in your heart, and lingers there for some time. Temptations always gather strength over time. All sin begins in your heart; adultery is an outworking of sinful desire becoming sinful action. Don’t kid yourself that you’re immune.
The more you allow that to sit in your heart and fester, the harder your heart is getting. That’s a spiritual disaster. You are hardening your heart against God. That’s why Jesus uses such strong language about gouging your eye out or cutting your hand off: Your lust is leading you to hell itself.
He goes on, quoting Deuteronomy 24:1 again. Read Matthew 5:31-32.
In a marriage union, two are one. If one person joins with someone else, they’ve broken the union that God set up. Adultery is spiritual as much as physical. And in the case of a Jewish man divorcing his wife (which must have been without adultery, since that would have led to her death), he’s spiritually still one with her. If he goes off with someone else, she’s free to remarry. But if he doesn’t, and she remarries, he’s made her into an adulterer! However you look at it, divorce without reason and adultery are spiritual disasters.
Call to repentance
Now get this: The Sermon on the Mount in Matthew 5-7 is meant to highlight to you just how sinful you are: More than you knew. From that, Jesus wants you to repent. Turn from sin, turn to him.
Many people have messed up in many ways. Every Christian has. There’s no such thing as a Christian who’s here on merit. Every Christian is nothing more than a forgiven sinner.
Jesus is calling you to himself, to cry to him for forgiveness. He will forgive you everything. Then, as you live for him, you will want to live differently.
He does not want you to enter hell; that’s why he took the punishment you deserve at the cross. Go to him and live. Today.
And because Christians are still sinners (though forgiven), we still sin, and we’re still liable to sin even in adultery. So:
Beware the pitfalls
Don’t assume you’re never going to fall. The devil is waiting to trip you up.
Even if you don’t think you will fall in any of these ways, the principles still apply to your particular weaknesses.
Deliberate seduction
First, beware deliberate seduction. The book of Proverbs has much to say about this: Read Proverbs 7:6-10, 21-23.
Sometimes, the lure into adultery or sexual sins will come from others who are directly and deliberately out to seduce you. You might not be looking for it. You might even miss the overt enticements. But sooner or later you’ll become aware of it. What will you do? Read Proverbs 7:24-25.
Don’t kid yourself that you weren’t aware. There comes a point when it becomes obvious. “Don’t let your heart turn aside to her ways. Don’t stray onto her paths.”
This applies even more widely than you’d like to admit. Social media algorithms are designed to entice you. The moment you click on something unhelpful, the more of it you’ll see. Worse still, the devil knows your weaknesses. He is always out to seduce you to sin. He knows what you like, and he know what you’re like. Don’t let your heart turn aside; don’t stray onto her paths.
Negligence
Here’s another danger: Negligence (and over-confidence). You might remember David and Bathsheba in 2 Samuel 11. He wasn’t where he should have been. His negligence meant he got caught up with the married woman Bathsheba.
You might not be out to begin an affair. The other person might not either. Yet, in careless negligence, you allow yourself to be in situations that lead you into sin. Proverbs 6:27-28 Can a man embrace fire and his clothes not be burned? Can a man walk on burning coals without scorching his feet?
In a work environment, that can be difficult. In a work environment you’re often in 1-to-1 meetings with people of the opposite sex. Don’t be negligent. Do your job well, and leave it at that. Satan will catch you out when your guard is down.
Good deeds gone bad
A third danger is even more tricky: Good deeds gone bad.
I know of a married Pastor where there was a young woman in his church doing some theological training. He mentored her. They had stimulating, spiritual, theological discussions. But it didn’t end there.
I heard of another example where a man was drawn to help a woman in her situation. His action was prompted by genuine concern and pity.
In both cases, the men’s hearts were drawn towards the women with good motives. But your heart isn’t to be trusted.
So know your own heart. Satan is the Tempter, and his aims are simple:
- To get you to sin.
- To ruin your relationship and witness to Jesus.
Satan will persuade you of your strength against temptation because of your faith… then he’ll burn you, along with your faith. No past triumph will protect you. The battle is now.
Can you see it in your life?
- It might be a sexual sin, but it could be anything.
- Do you have a cooling off in your zeal for God?
- Do you imagine or meditate on sin, rather than holiness?
- Is there a dulling of your prayer life and relationship with God in prayer?
No wonder Jesus’ command to his disciples was “Stay awake and pray, so that you won’t enter into temptation. The spirit is willing, but the flesh is weak.” (Matthew 26:41)
But if these are the pitfalls, what can you do positively?
Remain in Christ
Whether you have fallen or are at danger of falling, start with the Lord. Stay awake and pray. Soften your hard heart again. Consider the sin that you’re tempted towards and thing, “Jesus was punished for sin like that? How can I add to his pain?”
Repent of your sin. There’s no end to repentance in the Christian life, because there’s no end to your sin (in this life). So repent, and go back, back, back to Jesus.
And if you’re entangled in a sinful state or relationship, dig yourself out. There is no suggestion that that would ever be easy; lives are messy and sin is the messiest part. But repentance and faith mean nothing if not accompanied by action. Dig yourself out of that hole. You can do it. Christ is your strength.
If you’re in a state of temptation, and you think you’re not sure if you can stand, pray for help.
You have the Holy Spirit of God within you.
- 2 Timothy 1:7 “For God has not given us a spirit of fear, but one of power, love, and sound judgment.”
- Galatians 5:22-23 lists says “the fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faithfulness, gentleness, and self-control.”
- 1 Corinthians 10:13 “God is faithful; he will not allow you to be tempted beyond what you are able, but with the temptation he will also provide the way out so that you may be able to bear it.”
Job didn’t have the Holy Spirit in him has you do, but he could say “I have made a covenant with my eyes. How then could I look at a young woman?” (Job 31:1)
By the Spirit, put to death the sins of your body.
Flee temptations; resist the devil. You can’t do those things on your own, but by the Spirit of Christ you can.
Delight in your love, your friend
Proverbs had some dire warnings, but it has very positive encouragements too:
- Proverbs 5:15-19 urges you to delight in your own wife: “take pleasure in the wife of your youth”.
- Song of Songs is full of the delight between a man and a woman: In Song 5:16, woman simply says, “This is my love, and this is my friend.”
Married people, take delight in one another as a couple.
But those exhortations are to all of us as the bride of Christ! Take pleasure in him, your love, your friend. Remain in joyful, faithful, committed love for God in Christ.
He will enable you to remain in joyful, faithful, committed relationships in life.
Spiritual adultery and marital adultery go hand in hand to destruction.
But delight in Christ, keeping close to him in daily communion, will guard your heart from a multitude of sins, and keep your path from temptation’s paths.
Beware the spiritual dangers; beware the pitfalls; remain in Christ. He will never, ever disappoint you.