Sermon: Sunday, 30th November, 2025
Speaker: John Johnstone
Scripture: Matthew 5:27-30
As we continue the most famous sermon ever preached, Jesus’ Sermon on the Mount, we have reached the section dealing with adultery and lust. I hope that all of us can see that Jesus’ teaching is much-needed in our churches today. This is a sensitive area. Many of us will have committed sexual sin and some of us will have been victims of adultery. All of us will have experienced problems in our hearts with lust. Some of us might be addicted to sexual sin. From the outset, it is important to say that no matter what we have done in the past, in Jesus we can always find forgiveness and the power to change. The mistakes of our past do not need to define us forever. There is hope for those caught up in sexual sin. ‘I have not come to call the righteous, but sinners to repentance.’ (Luke 5:32)
Let’s start off by saying that when Jesus speaks to us about the boundaries of sexual behaviour, both in physical acts and also in our thought lives, he does so as the Creator of the world, whose boundaries are wise and given because he loves us. God invented sex. It sometimes feels like all the church ever says about sex is that it is negative. But that is not true. The Bible is extremely positive about sex. It is God’s gift to us. In its proper context, it is a wonderful expression of love to another person. There’s a whole book of the Bible, Songs of Solomon, devoted to the topic. Jesus is not old-fashioned or prudish when it comes to sex. It’s just that as our Creator, he sets the boundaries for sex, not us as individuals (doing what we like) and not society, whose values change over time.
The early chapters of Genesis give us the original context for sexual intercourse and show that God has designed this wonderful gift to be expressed within a lifelong marital relationship between one man and one woman. As they are joined together as husband and wife their unity and diversity is expressed: ‘So a man will leave his father and his mother and be united with his wife, and they will become one flesh.’ (Genesis 2:24) God has made us as sexual beings, and so in that sense it is a natural appetite. The problem is, our human appetites are now distorted by sin, and so now we sometimes use for evil what God created for good. We want to go our own way. We want to escape from God’s loving boundaries. Our sexual desires can be distorted, and when they are, they need to be resisted.
Amy Orr-Ewing: ‘What is wrong with sex before marriage? How about: ‘What is wrong with anything?’ In other words, where do you get the moral code by which you live your life? There may be a whole number of different responses: ‘I do what I feel is right’ – my morals are entirely personal and arbitrary. Or: ‘Society decides what is right and wrong’ – laws are made and as long as I stick within them everything is OK. Or anything in between those two responses. For us as Christians, right and wrong are not purely up to the individual; after all, what you feel is good for you may hurt me. It is not only up to society either; lots of societies have allowed things to be ‘legal’ that you or I might take issue with. Right and wrong for the Christian come from a higher standard than any individual or group of humans – they come from God. The creator is also the moral lawgiver. So, when I say that I believe that sex is designed to be expressed within marriage, I am not setting myself up as judge and jury and deciding to make life difficult for single people – I am trying to follow the maker’s instructions.’
1.The act of adultery is wrong
We all know the seventh commandment: ‘You shall not commit adultery.’ (Exodus 20:14) Most of the Pharisees believed they managed to keep this commandment. It’s probably true that most of them had not committed the outward act, though many of them facilitated easy divorces so that men could indulge their desires for other women but still be viewed as righteous. This was, of course, total hypocrisy. It is good for us to remind ourselves of how devastating adultery can be to families. One of the most famous adulterers in the Bible is King David. His story reminds us that adultery breaks several of the 10 commandments at once, not just the 7th. David steals the wife of another breaking the 8th commandment. He covets his neighbour’s wife breaking the 10th commandment and this leads him to murder, having Uriah the Hittite killed, breaking the 6th commandment. Lust, left unchecked, can lead to absolute disaster.
A Christian man committed adultery and eventually met up with his pastor. He defended his act. He wasn’t looking to have an affair. He and his secretary just fell in love. How can that be wrong? They couldn’t help themselves. It just happened. ‘Pastor, I know it was wrong. But really—nobody got hurt. It was a private matter.’ The pastor quietly listened and then replied: ‘Nobody got hurt? Thirty people have already come to me in tears because of what you did.’
He went on to list the kinds of people affected: the man’s wife, broken and humiliated. His children, confused and wounded. The children of the woman involved. The man’s extended family. The church leaders, shaken and grieved. The friends who felt betrayed. members of the church who struggled with trust. New believers whose faith was unsettled. Unbelievers who mocked the name of Christ. Sin always has ripples far beyond what the sinner imagines. In other words, God forbids adultery because it wrecks families and scars our children and emotionally and psychologically damages our spouse and others. It leaves people broken-hearted.
Before we move to lust, let’s be clear: Jesus says marriage is the only context for sexual activity. So, if any of you are breaking that command, then if you want to take following Jesus seriously, you need to stop. Wait until you are married. This is God’s boundary for true joy in sexual relationships – a context of life-long commitment and love. Is there something you need to stop doing?
2. Adultery in our thoughts is also wrong
Over the last 60 years, since the 1960s, the sexual ethics of most people have radically changed, drifting further and further from what the Bible says. We all know this. Many people think it is ridiculous to confine sex to the context of marriage. For many people, anything goes, as long as you don’t harm anyone. But here, Jesus swims against the tide of our culture. He goes in the opposite direction. Jesus does not limit the reach of the 7th commandment to just the act of adultery but explains to us that it also includes the lustful look: ‘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.’ (Matthew 5:27-28)
What is Jesus doing here? Jesus is pointing out that the root of adultery lies in the lust in our hearts. Jesus has already explained that unrighteous anger breaks the 6th commandment – do not murder. In the same way, Jesus deepens and widens the reach of the 7th commandment. Lustful thoughts in our minds break the spirit of this command. Lustful thoughts are wrong. It is not wrong to look at someone and admire them but when we look in a lustful way, we begin to desire what is not ours to have, and we allow our imaginations to run riot. Which of us is a stranger to such thoughts?
Friends, lust has always been a massive problem in the human heart. We need to be honest about that. And in 2025, if anything it is becoming harder to remain pure in the sexual arena. We are bombarded with sexual images on films, adverts, the internet and in fact, almost everywhere. Here are some shocking facts to underline this. The average age children see pornography in the UK is 13. It is accessed 1.4 million times per month by British children. The UK has one of the highest rates of visiting pornographic sites in the world. This means that porn is often the starting point for young people when it comes to sex. 25% of search engine requests are pornography related. 30% of church leaders access porn more than once a month. 75% of Christian men view pornography on a monthly basis (figures from CARE). Why? They might feel it is private, that it does not hurt others, and that it gives them freedom. The opposite is actually the case.
3. Jesus tells us to get practical – have a plan to counter lust
‘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.’ (Matthew 5:29-30)
Jesus’ warning is graphic because he knows where lust can lead. David’s lustful look at Bathsheba on the roof of his palace led to mayhem. Our lustful look at a person or a person on a screen can also lead to mayhem. Never think, ‘This will never happen to me,’ Lust and sexual sin are highly addictive and always leave us wanting more. They promise much but deliver pain ultimately. Of course, Jesus is speaking in hyperbole here – he does not want us to cut off any body parts. His point is this: take immediate and urgent action against lust before it gets out of control. Lust is not your friend but your enemy. Have a plan to counter lust.
So, for us, to gouge out an eye might mean that we refuse to watch certain movies or TV programmes. We might decide against reading a novel if its erotic content leads us to lustful thoughts. We might need to install software on our laptop, phone or tablet, so prevent us from seeing certain things. We might need to stop clicking on certain things we come across on the internet. We might have to say, ‘No.’ to someone we like who wants to meet us for a drink, because we or they are already married.
And here’s a really hard but important practical step. We might need to admit to a friend in the church or another Christian that actually we do have a problem with lust and porn, and ask them to help you keep accountable to them. If someone asks you regularly about these things it is so helpful, because it is so hard to break the patterns on your own. And I hope it goes without saying that we need to confess our sins in this area and ask for the Holy Spirit to give us power to resist temptation. This is basic Lord’s Prayer stuff – ‘Lead us not into temptation.’ (Matthew 6:13)
When someone goes to the gym in order to strengthen their muscles, what do they do? They have to resist the force of the weights they push against. As they resist, they get stronger. The same is true spiritually. Expect the temptations still to come but be ready to resist them.
Here’s the thing – we are all fallen human beings and that means many of our desires must be resisted. If I often have the desire to eat far more food than I need, I need to resist this wrong desire, otherwise I will develop significant health issues. Sometimes we have lazy desires and might not bother doing the work we need to do. We need to fight this desire. If we have enough resources but have a love of money, with an unhealthy desire for getting more and more, we need to resist these selfish and destructive desires. The truth is that we have many desires which lead us away from loving God and loving our neighbours. We need to resist them all. Lust is another of these desires.
Vaughan Roberts: ‘The modern idea is that we have to affirm the feelings we have and that we can only be authentic as we fulfil our desires. But the Bible teaches that some of our desires should be resisted. We are to measure our desires and feelings against the will of God, as the Spirit through the Bible makes us sensitive to those things that grieve him, and helps is to want to live in the ways that please God.’
In other words, part of being a disciple of Jesus is this tug-of-war experience. Sometimes the good we want to do we do not do and the things we don’t want to do we end up doing. So, we need to pray for help, and we need to resist wrong desires. We need to understand that lust never delivers what it promises. And we need to believe that true and lasting joy and satisfaction only come through living within our Maker’s boundaries. Jesus himself is the water of life who can satisfy our deepest desires.
And if you carry the burden and guilt of sexual sin, then take it now to God in prayer. Remember what happened to the prodigal son who returned to his father – he was welcomed with open arms.