The Sixth Commandment

The Sixth Commandment

What is the sixth commandment?

You shall not commit adultery.

What does this mean?

We should fear and love God so that we lead a sexually pure and decent life in what we say and do, and husband and wife love and honor each other.


In the fourth commandment we learned about the gift of parents and authorities and the honor, love, and respect we owe them. In the fifth commandment we learned about the gift of life and the help and support owed our neighbors in keeping and protecting it. In the sixth commandment we come finally to the gift of sex and the purity and decency with which we ought to guard it. 

Luther’s explanation of this commandment is rather unique in view of the previous four explanations. The explanations of commandments two through five have all explained the commandment with reference to the first commandment and via negative prohibitions and positive commands, “don’t do’s” and “do do’s.” It is immediately striking that the sixth commandment is explained in entirely positive terms with no negative prohibitions. Luther does not provide a list of sexual sins to avoid. In view of the New Testament’s rather graphic descriptions of all the ways that one can break the sixth commandment, this might seem like a weakness on the part of Luther, but the reason for this harkens our attention back to the original purpose and audience of the catechism. The Small Catechism is a “children’s” catechism and thus the goal is to teach children how to act, not to incite the imagination toward sexual sins. For an audience that is not versed in sexual relations, marriage, or even any serious romantic relationship it is enough to deal with the commandment, “in a simple way.” We who live in the wake of the sexual revolution might even take a page from Luther’s book in practicing the same modesty in our own instruction of the youth. Because our instruction is primarily for those beyond adolescence, we can deal with the present topic with the same chastity, but in greater detail.

In order to answer, “What is adultery?”, we might begin by asking, “What is marriage?” The foundation for our understanding of gender, sexuality, and marriage comes from Genesis 2:15-24. After creating, ordering, and filling the heavens and the earth, God finally sets about creating the crown jewel of his creation, man. God creates Adam from the dust of the earth and breathed into him the breath of life. And after five days of God creating and us hearing the refrain, “and it was good,” on the sixth day we hear something rather alarming after the creation of Adam: “It is not good…” Specifically, it is not good, “that the man should be alone.” And thus, God sets about the task of getting Adam a “helper fit for him.” But God goes about doing this in a rather circuitous way. First, he parades all the animals of the earth before Adam to see if he would find a helper. Adam names all the creatures, thus establishing his dominion over them, but “for Adam there was not found a helper fit for him.” Thus, God causes Adam to fall into a deep sleep, he takes one of his ribs, and from this rib God forms the Woman. When Adam wakes up, God walks Eve down the aisle like a father would his daughter, puts Eve’s hands in Adam’s, and here Adam speaks the first poem ever composed by man: “This at last is bone of my bones and flesh of my flesh; she shall be called Woman, because she was taken out of Man.” After this good confession, Moses includes some brief commentary on the significance of this moment. “Therefore a man shall leave his father and his mother and cleave to his wife, and they shall become one flesh.” Moses recognizes this story as the divine institution of marriage and confesses that all marriage flows from the marriage of Adam and Eve. In addition to this institution narrative, we can also recollect God’s words from Genesis 1:28, where he commands man and woman to “be fruitful and multiply and fill the earth and subdue it, and have dominion…” With these commands and promises, we have a complete foundation for understanding marriage. 

To collect it into one sentence, marriage is a one-flesh union established by God’s word between one man and one woman for mutual service, joy, procreation, and the nurturing and raising of children. This is the understanding of the Old Testament and it is an understanding which is confirmed by the New Testament. Jesus says in Mark 10:6-9, “But from the beginning of creation, ‘God made them male and female.’ ‘Therefore a man shall leave his father and mother and hold fast to his wife, and the two shall become one flesh.’ So they are no longer two but one flesh. What therefore God has joined together, let not man separate.” Likewise, concerning marriage, Paul writes in Ephesians 5, “Wives, submit to your own husbands, as to the Lord. For the husband is the head of the wife even as Christ is the head of the church…Husbands, love your wives as Christ loved the church and gave himself up for her…” and Peter similarly writes in 1 Peter 3, “Likewise, wives, be subject to your own husbands… for this is how the holy women who hoped in God used to adorn themselves, by submitting to their own husbands as Sarah obey Abraham, calling him lord… Likewise, husbands, live with your wives in an understanding way, showing honor to the woman as the weaker vessel, since they are heirs with you of the grace of life…” Finally, the author of Hebrews writes to his congregation, “Let marriage be held in honor among all, and let the marriage bed be undefiled…” Thus, marriage is upheld by Christ and highly esteemed by Peter and Paul.  

With marriage firmly established, we can now discuss the rupture of marriage, adultery. At base, adultery is the act of sexual intercourse, in thought or deed, outside the estate of marriage between man and woman. Sex is created, designed, and given by God to happen within the estate of marriage. Sex outside of this estate, then, is adultery. Specifically, this includes cohabitation, fornication, promiscuity, and lust, alongside homosexuality, rape, incest, sexual abuse, the use of pornography, etc. Jesus says in his Sermon on the Mount, “You have heard it 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.” St. Paul writes in 1 Corinthians 6, “Or do you not know that the unrighteous will not inherit the kingdom of God? Do not be deceived: neither the sexually immoral, nor idolaters, nor adulterers, nor men who practice homosexuality, nor thieves, nor the greedy, nor drunkards, nor revilers, nor swindlers will inherit the kingdom of God.” Likewise in Romans 1, Paul writes, “For the wrath of God has been revealed from heaven against all ungodliness…For this reason God handed them over to dishonorable passions. 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.” 

Regardless of the ways in which people might break the sixth commandment, the right course of action with sin is always confession and absolution. The blood of Christ avails for all sins, no matter how grave or numerous. Private confession and absolution with a pastor is a wonderful evangelical service that Christians can make use of that is especially comforting in the realm of sexual sins which often bring great shame and guilt. To hear the words of forgiveness personally and privately is a wonderful blessing and I highly encourage you to take advantage of it.

Prayer: Holy Lord, you instituted marriage in Eden, and by your word you uphold and protect this blessed union of man and woman in one flesh. Cause us to honor marriage and put away from us all sinful thoughts, words, and deeds that would dishonor and distort the gift of marriage. Bless all married couples with faithfulness. Hear the prayers of all who seek a godly spouse, and give to us all purity and decency in all things; through Jesus Christ, our Lord. Amen.