Flee Adultery!

Catechetical sermons preached in PCC Evening Worship Services, Feb 2013 to Dec 2017

WSC 70-72 of 107

Thou shalt not commit adultery.

Exodus 20:14


A. The Seventh Commandment is, Thou shalt not commit adultery.1

1Ex 20:14.

WSC 71. What is required in the Seventh Commandment? 

A. The Seventh Commandment requireth the preservation of our own and our neighbour’s chastity, in heart, speech, and behaviour.1  

1 1 Cor 7:2, 3, 5, 34, 36; Col 4:6; 1 Pet 3:2

WSC 72. What is forbidden in the Seventh Commandment? 

A. The Seventh Commandment forbiddeth all unchaste thoughts, words, and actions. 1

1 Mt 15:19; Mt 5:28; Eph 5:3, 4

We have been studying the Ten Commandments as part of our study of the Scripture underlying the Westminster Shorter Catechism. It is hard to overestimate the importance of the Ten Commandments.  

Sin is lawlessness. Christ came to free us from the guilt and bondage of sin. All unbelievers are trapped in lawlessness. They are in bondage to sin. Apart from Christ, they will remain bound to eternal damnation. But all believers are enabled by the Spirit of Christ to flee lawlessness. Adultery is a form of lawlessness. Therefore, we must flee lawlessness.   

The Seventh Commandment, “Thou shalt not commit adultery,” demands that we flee adultery. But adultery affects not only married persons.  

Our Shorter Catechism, Question 71, asks: “What is required in the Seventh Commandment?” Answer:  

The Seventh Commandment requireth the preservation of our own and our neighbour’s chastity, in heart, speech and behaviour.

The next question (WSC 72) asks: “What is forbidden in the Seventh Commandment?” Answer:  

The Seventh Commandment forbiddeth all unchaste thoughts, words, and actions.

In this study, with the Lord helping us, we want to expand these propositions in an applicatory way. We have eight brief points according to the acrostic ADULTERY: 

  • All sexual indulgence outside marriage is unchaste 
  • Do not think that you are immune 
  • Unless you guard your eyes, you will fall 
  • Lust is best fled from, not fought 
  • Treat others as brothers and sisters 
  • Earlier marriage may be the solution for some 
  • Remember your marital vows and duties 
  • Yield not to a moment’s pleasure but to Christ 

1. All Sexual Indulgence Outside Marriage Is Unchaste 

Marriage was instituted by God. One of the purposes of marriage is that there may be an increase of mankind, and that the church may be furnished with a holy seed. Thus, when God gave Eve to Adam, He commanded them: “Be fruitful, and multiply” (Gen 1:28). 

To fulfil this purpose, God has created in men and women the ability and a powerful desire to procreate and to demonstrate love and affection physically. This desire is good and beautiful in and of itself. 

However, this desire and its associated acts are intended by our Creator to find expression and fulfilment only within the confines of marriage.  

The apostle to the Hebrews says: 

Marriage is honourable in all, and the bed undefiled: but whore-mongers and adulterers God will judge.

Heb 13:4

So, when God says, “Thou shalt not commit adultery,” to be specific, He is prohibiting all sexual expressions outside the confines of legitimate marriage.  

We don’t have to go into details. The Word of God has many examples. Obviously, any marital infidelity or extramarital affairs—as in a sexual relationship outside the bounds of one’s marriage is forbidden. But so is fornication or carnal relations between two unmarried persons. “Flee fornication. Every sin that a man doeth is without the body; but he that committeth fornication sinneth against his own body,” says the apostle Paul (1 Cor 6:18). Likewise, incest, polygamy, homosexuality, etc, are forbidden by the Seventh Commandment. Indeed, even if the civil legislature of the land allows for homosexual marriages, incestuous marriages, polygamous marriages or even marriages between men and animals, the Seventh Commandment is still violated. Indeed, the nation is violating the Seventh Commandment when it allows such immoral marriages contrary to God’s law. 

Not only so, but when the Lord Jesus expounds the Seventh Commandment in His sermon on the Mount, He clarifies that if a man looks upon a woman to lust after her, he would have committed adultery with her already in his heart (Mt 5:28). And then He goes on to say that if your eyes cause you to sin, pluck it out and if your hands cause you to sin, cut it off. 

Undoubtedly, the Lord is saying that the Seventh Commandment can be violated by thinking, looking and touching. Thus, immodest physical contact between a man and a woman would be forbidden by the Seventh Commandment (cf. Gen 26:8-9a). But so would a lustful thought or a lustful look (cf. Eph 2:3). Needless to say, then pornography is a violation of the Seventh Commandment. It is not as harmless as some people suppose.  

The Seventh Commandment, in other words, is not just about adultery between married persons, but about any form of sexual immorality or uncleanness. And all sexual indulgences outside the bounds of legitimate marriage are unchaste whether it involves physical contact, or only gestures, words and thoughts.  

Of course, there is a difference in the degree of severity between the various ways of violating the Seventh Commandment. Actual sexual contact between two persons who are not married to each other is undoubtedly more sinful than a fleeting lustful thought. But bear in mind that both are a breaking of the Seventh Commandment and an ugly sin in the sight of God. 

2. Do Not Think That You Are Immune to This Sin 

Remember that this sin affects everyone. You and I, yes, every one of us, will be tempted to break this commandment. The pressure will come not just to unbelievers but to believers. Not just to weak believers, but to strong believers. Not just to the young, but to the old.  

Yes, it is true that once you are past your prime, you are less likely to fall into this sin, but do not take that for granted. Many who are way past their prime have fallen into this sin. 

Let us take heed lest we fall. Realise your weakness and potential to fall before it is too late. Many a great man has fallen into temptation and sinned in this area. I do not think any of them thought they would fall in this way.  

Again, Scriptural examples abound. We think of Samson, David and Solomon. Samson was one of the strongest men who ever lived. David was a man after God’s own heart. Solomon was the wisest man in his time.  

Likewise, in the history of the Church, there have also been great men who had fallen into this sin, though often before their conversion. We think of how Augustine, the great theologian, had a concubine whom he never married, and even a son with her. We think of the Swiss Reformer Ulric Zwingli, who fell into fornication early in his ministry. Though he repented, it was a thorn in his side for much of his life.  

Likewise, in modern times, we’ve heard about ministers of the Gospel falling into such grievous sin—many of them are still alive; some have been defrocked; some are still in the ministry, sadly so. Some of these are even popular writers and preachers.  

This sin affects everyone: young and old, lay persons and ministers, male and female.  

The Dutch American theologian Cornelius Van Til was about eighty years old when he urged his students to resist the temptation to fall into adultery. A twenty-year-old student told him: “It is OK for you, professor. You are an old man, but I am a young man.” The professor replied: “Yes, but the temptation I knew as a youth is the same temptation I face today.”  

Dr John Gerstner was also in his eighties when he was asked to preach on “Sin and the Pastor.” Amazingly, the only sin he spoke about in his sermon was that of breaking the Seventh Commandment! Yes, we will fail in the other commandments too, but the pressure to break the Seventh Commandment is particularly acute.  

Brothers and sisters, and youths, take heed lest ye fall! Know your vulnerability. The most steadfast Christian is also vulnerable in this area.  

Resist the temptations that you will definitely face. Yes, every day when you watch the television or internet movies, you will be eroding your resolve against this sin, for the television almost consistently portrays adultery and fornication as being acceptable, natural and even beautiful. But oh, pause for a moment to think: what makes us different from animals if adultery and fornication are natural? But God has spoken: “Thou shalt not commit adultery.” Do not imagine that you are immune to this sin. 

3. Unless You Guard Your Eyes, You Will Fall

The Lord was tempted in all points, like as we are, yet without sin. He knew that the sin of adultery begins with the eyes. Thus, He focused on the eyes when He expounded the Seventh Commandment. If your eyes cause you to sin, pluck them out, He says. 

The sin of breaking the Seventh Commandment almost always begins with the eyes. Unless you guard your eyes, you will fall.  

David’s adultery began with his eyes. He saw, and he took a second look and continued his gaze. And lust overwhelmed him and he gave in to all the temptations that proceeded. How many instances of adultery and fornication could be avoided were the eyes first disciplined to look away whenever a sight could give rise to temptation?  

Is there a scene on TV which may tempt you or erode your sensibility? You may want to switch it off or at least look away. Is there a picture on the internet page that provokes lust? Do not gaze at it. Instead, close the window. Is there a poster on the MRT which causes unwanted passion to arise in your heart? It may not be wise to continue standing in front of it. Move away! Is there someone dressed provocatively in front of you? Look away!  

Yes, sisters, you have a responsibility in the way you dress. You can help the brothers in the church by dressing modestly.  

And brothers, let us learn from the patriarch Job. He said: “I made a covenant with mine eyes; why then should I think upon a maid?” (Job 31:1). Yes, by all means, make a covenant with your eyes. Resolve never to gaze long at a woman unless she is your wife.  

Remember that the sin of breaking the Seventh Commandment almost always begins with the eyes. Unless you guard your eyes, you will fall. Think of how a king will defend his castle. He knows that he must hold the enemy outside at all costs. Once the enemy troop gets past the gate, the battle is lost. So don’t let the enemy troops get in by gazing and staring. Cut down every enemy soldier that chance to get in. 


4. Lust Is Best Fled From, Not Fought 

When danger confronts us, we can either fight or take flight.  

But what does the Scripture say regarding the danger of violating the Seventh Commandment? “Flee fornication” (1 Cor 6:18); “Flee also youthful lusts” (2Tm 2:22); “Abstain from all appearance of evil” (1 Th 5:22). 

I speak particularly to our younger unmarried persons. If you are in a courting relationship, it is natural that you want to spend time alone together to talk, to share and to pray. But take heed that you be not so alone that the temptation to be physical hounds you.  

Avoid travelling overseas together alone. Refuse to lock yourself in a room together. Many have fallen into fornication and adultery because they have given in to temptation in such a situation.  

Remember Joseph? Potiphar’s wife repeatedly tried to seduce him to be with her or to lie with her. Joseph was the second man in Potiphar’s household. All things were committed to him. But he knew Potiphar’s wife was forbidden territory. And he knew that it would be great wickedness and sin against God for him to give in to her seduction. So he would not even be with her, not to mention lie with her. But one day, he went into the house to do some business. It happened that he was alone, and Potiphar’s wife grabbed him by his garment. What did the godly man do? We are told he fled so hastily that he left his garment behind. 

Have you got yourself into a situation of temptation? It is no time to pray: “Lord, help me to overcome the temptation.” It is time to flee. Flee for the sake of your soul. 

“Flee fornication. Every sin that a man doeth is without the body; but he that committeth fornication sinneth against his own body” (1Cor 6:18). Flee if you love the person you are with. A moment of weakness, a moment of pleasure, but it may be a lifetime of regret. “Submit yourselves therefore to God. Resist the devil, and he will flee from you” (Jms 4:7). 

5. Treat Others as Brothers and Sisters 

This should especially be the case for members of the church. Paul says in 1 Timothy 5:1-2: 

Rebuke not an elder, but intreat him as a father; and the younger men as brethren; The elder women as mothers; the younger as sisters, with all purity.

Notice the qualification, “with all purity”? The apostle is aware of how the men of the church can easily be tempted to think impurely about the sisters around their age. 

Paul’s advice is that we must think of each other as brothers and sisters.  

Yes, it is possible that courtship and marriage relationships could arise within the church. But every believer must be careful to maintain decorum and purity. A man must not relate to a woman in the church in a way that he would not relate to his sister. Likewise, a woman must not relate to a man in a way he would not relate to her brother. In other words, there is really no place for seductive dresses, talks and actions in the church. 

Even courtship should be conducted with all purity! So, brother and sisters, if you want to know whether your behaviour towards another is appropriate, consider whether you would do it to your sister or brother. Remember: Treat members of the opposite gender around your age as brothers and sisters in Christ, with all purity. 

But now, sixthly, I must add that… 

6. Earlier Marriage May Be the Solution for Some 

Our Confession of Faith teaches us that one of the purposes of marriage is for the prevention of uncleanness. This is a biblical idea. The apostle Paul says:  

…to avoid fornication, let every man have his own wife, and let every woman have her own husband. … But if they cannot contain, let them marry: for it is better to marry than to burn.

1 Cor 7:2, 9

Calvin has rightly noted, I believe, that “[celibacy] … is an excellent gift; but is given only to a few” (Cor 1.232).  

So, beloved, if you cannot contain, begin praying that the Lord may provide and lead you towards marriage. The Lord is a God who cares about our well-being. He does hear and answer our pleas—sometimes unexpectedly. 

And if you are in courtship and you cannot contain, do not continue to postpone marriage to the point that you sin by way of fornication. Talk to your parents. Talk to your pastor and elders. Consider getting married earlier. It is better to marry early and suffer some hard knocks than to marry later and sin by way of fornication because you cannot contain. 

But seventhly, for those who are married: 

7. Remember Your Marital Vows and Duties 

Remember that God hates adultery. Remember that God hates the breaking of vows.  

Are you tempted to have a relationship with someone other than your spouse? Remember your vows. Remember the words of Malachi that “the LORD hath been witness between thee and the wife of thy youth … therefore take heed to your spirit, that ye deal not treacherously” (Mal 2:14, 16). 

Remember your marriage vows. Giving in to the temptation of adultery is a most terrible betrayal which shows your hatred for God and your spouse. 

Moreover, apart from remembering your vow, you must help one another by performing your marital duties, as Paul teaches us in 1 Corinthians 7.  

Again, I do not need to say much. Many adulteries in marriages have occurred because the couple has not maintained a healthy conjugal relationship.  

Beloved, if you are married, it is your duty to each other. It is commanded of God. Fail in this duty, and you must know that you are partly to be blamed if your spouse gives in to the temptation to break the Seventh Commandment. No, your errant spouse has no right to use your failure as an excuse for his or her wicked infidelity, but your conscience will undoubtedly accuse you. 

Finally, … 

8. Yield Not to a Moment’s Pleasure but to Christ 

I speak to you, brothers and sisters in Christ. I want to remind you that you will all face the pressure to break the Seventh Commandment, but you don’t have to give in. You are a new creature in Christ. Christ has not only paid your sin on the cross. He has freed you from the bondage of sin and Satan.  

Therefore if any man be in Christ, he is a new creature: old things are passed away; behold, all things are become new.

2 Cor 5:17

Listen to the Apostle Paul in Colossians 3: 

“ If ye then be risen with Christ [so you are no more dead in sin], seek those things which are above, where Christ sitteth on the right hand of God. 2 Set your affection on things above, not on things on the earth. [Do not give in for a moment of pleasure]  3 For ye are dead, and your life is hid with Christ in God. 4 When Christ, who is our life, shall appear, then shall ye also appear with him in glory [for you belong to Christ, so you will stand with him in glory! Would you give occasion for others to blaspheme Christ your Lord?]

5 Mortify [i.e. put to death] therefore your members which are upon the earth; fornication, uncleanness, inordinate affection, evil concupiscence, and covetousness, which is idolatry: 6 For which things’ sake the wrath of God cometh on the children of disobedience: 7 In the which ye also walked some time, when ye lived in them. [I.e. Remember: God is angry with such sin. You had lived without regard of God and sin in those ways. You were under the wrath of God, but now you are changed. You are a new creature. You do not need to live like the world any more.] 

8 But now ye also put off all these; anger, wrath, malice, blasphemy, filthy communication [i.e. immoral jokes, etc] out of your mouth. 9 Lie not one to another, seeing that ye have put off the old man with his deeds; 10 And have put on the new man, which is renewed in knowledge after the image of him that created him: 11 Where there is neither Greek nor Jew, circumcision nor uncircumcision, Barbarian, Scythian, bond nor free: but Christ is all, and in all.

Col 3:1-11

You, dearly beloved brothers and sisters, will come under the assault of Satan to break the Seventh Commandment. But you can help it if you are in Christ. For Christ’s sake, resist the devil. Yield not to a moment’s pleasure. Yield instead to Christ. Be holy as Christ, who redeemed you by His precious blood, is holy.


Here, then, are the eight lessons on the Seventh Commandment, once again: 

  • All sexual indulgence outside marriage is unchaste 
  • Do not think that you are immune to this sin 
  • Unless you guard your eyes, you will fall 
  • Lust is best fled from, not fought 
  • Treat others as brothers and sisters 
  • Earlier marriage may be the solution for some 
  • Remember your marital vows and duties 
  • Yield not to a moment’s pleasure but to Christ 

Have you been toying with adulterous thoughts? Have you secretly broken the Seventh Commandment and refused to acknowledge your sin? Would you not go before the Lord to humbly repent of your sin and your excuses? 

Is there anyone in our midst who has committed adultery, not just in the thought or eyes, and your conscience constantly pricks you every time you think about what happened? I want you to know that there is forgiveness in Christ. Remember how the Lord dealt with the woman caught in adultery? He dealt most gently with her and told her: “Neither do I condemn thee: go, and sin no more” (Jn 8:11).  

Cast your burden and guilt on the Lord Jesus Christ. He can heal you of your guilty conscience, and He alone can forgive you. But go and sin no more.  

David found forgiveness in the Lord, though he committed murder and adultery. All who go unto the Lord Jesus Christ sincerely will know His grace. He will in no wise cast you out when you go to him. Only turn away from your sin and go to him that He may wash you whiter than snow in the fount of His blood. Amen.  

—JJ Lim