Catechism Series: The Sixth Commandment
Exodus 20:14, Matthew 5:27
October 29, 2023

Grace, mercy, and peace from God our Father and from our Lord and Savior Jesus Christ.

The texts that I have chosen for this morning’s sermon is Exodus 20:14, “You shall not commit adultery.” and Matthew 5:27-28, You have heard that it was said, ‘You shall not commit adultery.’ But I say to you that everyone who looks at a woman with lustful intent has already committed adultery with her in his heart.”


To prepare for today I read a sermon on the Sixth Commandment by a Lutheran pastor from 1903.  He starts by saying the Sixth Commandment is one that would be easy to skip because it makes people uncomfortable.  However, since it’s God’s Law, he’ll address it with reluctance and tact.  In the second half of the sermon, he focuses on the dangers of attending the theater and dances, of wearing the wrong style of clothing, of reading the wrong types of books, and making the wrong kinds of friends.  Like Pastor Golladay, I thought about skipping ahead to the Seventh Commandment, but I can’t do that, regardless of my, or your, level of discomfort.  I’m not going to preach on the dangers of dancing but we do have to address this commandment because while on the surface the Sixth Commandment addresses adultery, below the surface is a sin unlike the others.

It’s common for Christians to say that all sins are the same in God’s eyes, and while it’s true that God hates all sin, He warns us that some sins are worse than others and have far graver consequences, and adultery is a perfect example.  If you commit murder, you’re sinning against the one you murdered.  If you steal, you’re sinning against your victim.  If you don’t worship regularly, you’re sinning against God.  While the sin of adultery can take many forms and may or may not involve sinning against someone else, it’s always a sin against yourself.  Whether it’s surfing the internet looking at pornography, constant lusting over men or women, physical relations outside of marriage, living together before marriage, cheating on your spouse, or homosexual behavior and desires, each of these corrupts your heart.  Saint Paul says Flee from sexual immorality.  Every other sin a person commits is outside the body, but the sexually immoral person sins against his own body (1 Cor 6:18).

God reiterates throughout the entire Bible that sexual immorality is not an insignificant sin, and that it’s a sin which infects the heart and mind.  If you list all the sins mentioned in the Bible by the frequency of God’s condemnation, sexual immorality, in whatever form, would be right near the top of the list.  When you sin against your own body, especially when your conscience is screaming at you to stop, you’re filling your heart with an acid that eats away at what is good.  And it will keep eating away until you either stop and repent or become so desensitized to your sin you don’t see that it’s wrong.  Paul describes the unrepentant this way: For although they knew God, they did not honor Him as God or give thanks to Him, but they became futile in their thinking, and their foolish hearts were darkened(Rom 1:21).

What God says about sexual immorality applies to everyone; no one is exempt.  However, when Christians break the Sixth Commandment, we’re not just sinning against ourselves, we’re sinning against God who lives in us.  The Lord says, Do you not know that your body is a temple of the Holy Spirit within you, whom you have from God?  You are not your own, for you were bought with a price (I Cor 6:19-20).  When Christians engage in sexual immorality, we’re desecrating the Holy Spirit’s temple.  We’re polluting what God made beautiful and holy in our baptism and when we were brought to faith.  We’re called to honor this temple, but our immorality dishonors it and heaps guilt and shame upon it.

When Adam sat in the Garden that first day, he lacked a helper.  The creation of Eve from his rib gave him a helper and a mate.  With the first couple, God instituted marriage, and their marriage became the model for all that followed.  It’s the model which provides a man and woman with companionship, a place for God-pleasing procreation, and the only place romantic passion is to be enjoyed.  When sexual immorality interferes, it spoils what God created.  God says, Let marriage be held in honor among all, and let the marriage bed be undefiled, for God will judge the sexually immoral and adulterous (Heb 13:4).  When a spouse watches pornography it defiles their marriage which was blessed by God.  When one party has an affair, it defiles what was instituted by God.  When couples divorce, it tears apart what God put together.  The marriage bed is a sacred place, for one man and one woman, who are married.

The defiling of the marriage bed occurs not just within marriages, but outside them as well.  Co-habitation, acting like you’re married when you’re not, announces that marriage is unnecessary, that it can be temporary, and easy to walk away from.  Couples who cohabitate have poor outcomes when compared to couples who waited until they were married to share a bed.  Even if the statistics were wrong and pretending to be married was a good thing, God still says it’s not.  Pre-marital sexual relationships defile each party, and it doesn’t matter if it’s a one-night stand or a long-term relationship, if love’s involved or not, the couple has become one flesh, and this flesh cannot be ripped apart without leaving scars.

Homosexuality, while widely accepted, is a grave offense against the Sixth Commandment because it goes against nature.  God says, For their women exchanged natural relations for those that are contrary to nature; and the men likewise gave up natural relations with women and were consumed with passion for one another (Rom 1:26-27).  This is a touchy subject, I get it.  Christians come down on all sides of the debate.  It stirs up all sorts of feelings and opinions, but feelings and opinions don’t matter when God’s Word is involved.  The Lord says quite clearly that those who persist in an unrepentant lifestyle, whether it’s heterosexual, homosexual, or some other sort, will not have a place in heaven.  I’m not saying homosexuals are bad people or should be attacked, that’s nonsense.  What they need is to be shown the love of Christ and the forgiveness of sins which comes to all who repentant and seek His grace.  Christians who struggle with homosexual impulses or desires need to know that their preferences don’t determine their identity.  Your identity is found in Christ as His baptized people, who can turn to Him for help in whatever temptation or sins you face.  God doesn’t make us face temptations on our own and change is possible through by grace.

In First Corinthians Saint Paul says, Do you not know that the unrighteous will not inherit the kingdom of God?”  He then proceeds to name some of the sins of those who are unrighteous: sexual immorality, adultery, idolatry, homosexuality, drunkenness, and stealing.  But then he says about Christians: And such were some of you.  But you were washed, you were sanctified, you were justified in the name of the Lord Jesus Christ and by the Spirit of our God (1 Cor 6:9-11).  They were unrighteous, now through faith they are forgiven and transformed.  Sexual immorality is a serious sin against our ourselves, others, and most importantly God, but you’re never outside of forgiveness.  I know that violations of the Sixth Commandment can cause a lot of shame and guilt, but your baptism washes you of your sin and guilt, forgiveness restores your holiness, and by God’s grace you can move forward, changing your behavior, turning your back on what you were and seeing what you are.  There’s hope in God’s promises for all who struggle with their sins, for no one fights sin or temptation alone – God is always present to fight for you and through you because He lives in you.

In First Corinthians Paul wasn’t afraid to confront them on how they were breaking the Sixth Commandment.  Most pastors aren’t as bold as Saint Paul.  Since we’re afraid of making people mad so they leave the church, we avoid these delicate topics.  However, I’m told to preach the whole Bible, and so that’s what I did today.  I don’t want you to think that I’m just railing against all the things wrong with society.  I don’t want you to think I’m trying to shame you.  Instead, I’m following Paul’s example.  He says, I do not write these things to make you ashamed, but to admonish you as my beloved children (I Cor 4:14).  It’s actually God’s purpose more than anything.  He calls you to repentance because He loves you and wants you to know the joy of forgiveness and eternal life.  He crushes you with His Law and then He follows with the sweet balm of the Gospel; the truth that Jesus has paid for all your sins.  In Him you find forgiveness and a change of heart.  By His power, you will find a new life which rejects the old, and you will remember that what you were is not what you are.  You are child of God, washed in the water of baptism and in the blood of Jesus, and God’s holy temple.



Now the peace which surpasses all understanding keep your hearts and minds in Christ Jesus.  Amen