Lesson 8: You Shall Not Commit Adultery

From my new book, The Way of the Lord: A Study of the Ten Commandments. Click here to buy the book and Bible study so you can use it devotionally or work through it with a small group of Christian brothers and sisters… or to even give away to someone who desires to learn more about the way of the Lord.

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The commandment against adultery is reaffirmed several times in the New Testament, and therefore is clearly morally binding in the new covenant age as well. Jesus teaches about its deeper application to the attitudes of our hearts, saying, “Everyone who looks at a woman with lustful intent has already committed adultery with her in his heart” (Matt. 5:28). But God had already indicated the deeper application of this commandment when he said in the tenth commandment, “You shall not covet your neighbor’s wife” (Ex. 20:17).
The purpose of this commandment is to protect marriage… (Wayne Grudem)
 
ADULTERY — willful sexual intercourse with someone other than one’s husband or wife. Jesus expanded the meaning of adultery to include the cultivation of lust: “Whoever looks at a woman to lust for her has already committed adultery with her in his heart” (Matt. 5:28).
Adultery plays havoc with personal, domestic, and national happiness. A case in point is David’s affair with Bathsheba. Their adultery led to a cover-up, which was followed by the murder of Bathsheba’s husband (2 Samuel 11). Nathan the prophet later came to David, accusing him of his sin and declaring that because of it, violence would become commonplace in David’s household (2 Sam. 12:10). One disaster after another struck his family, including rape, murder, and revolt (2 Samuel 13–15).
Adultery reached epidemic proportions in Jeremiah’s time. The prophet repeatedly spoke out against this and other sins (Jer. 7:9; 23:10). The problem was so rampant that even the other prophets of Jerusalem were guilty of it (Jer. 23:14), and Jeremiah predicted God’s judgment on them (Jer. 23:15). (Nelson’s New Illustrated Bible Dictionary)
 
If we wish to avoid committing adultery, the [Westminster Larger] Catechism says, we should cultivate purity of heart in sexual matters, avoiding occasions of temptation, replacing such occasions with “diligent labor in our callings.” Such diligent labor might not seem at first to be an implication of the seventh commandment, but for those who seek sexual purity it is indispensable.
We can follow this line of thinking still further, however. Scripture represents marriage as a reflection of our covenant relationship with God. To violate marriage is to violate that covenant, and unfaithfulness to God is adultery. All sin is unfaithfulness to God, spiritual adultery. So the seventh commandment, like the others, actually covers all of life from its particular perspective. Whenever we sin, we can think of it as marital unfaithfulness. And we should think of it that way, better to understand our radical need of forgiveness from our heavenly husband. The seventh commandment’s perspective on sin is a radically personal perspective, presented in vivid, sexual imagery. It yields a powerful motivation for repentance. (John Frame)

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​Introduction
 
As the commandments we have looked at before, there is much more to this commandment than meets the eye. You can see why the Pharisees had an inflated view of their standing before God. They believed they were fulfilling the commandments because they had not killed anyone, robbed a bank, or run off with a neighbor’s wife.
 
Missing from their understanding were the issues of the heart that God cares much about. In fact, in 1 Samuel, God revealed that humans look at the outside things that characterize a person, while God cares more about the heart. It’s not just the Pharisees who were guilty of this. Christians too, to use Jesus’ satiric imagery, strain out gnats and swallow camels. Christians may think that because they have outwardly behaved themselves by not having sexual intercourse with another person, yet the epidemic of Christians (men especially) who watch pornography is shameful and astounding. If this isn’t a lustful desire of the heart, it’s hard to imagine what is.
 
The positive aspect of this commandment encourages us to learn ways to honor our marriages, if we’re married, and pursue fidelity in that context. If we are single Christians, we need to employ our Christian calling to chastity and learn ways to enjoy the riches of Christian fellowship.
 
Furthermore, as John Frame mentions in a quotation above, we need to learn that faithfulness in all areas of our lives is primarily faithfulness to God, whereas infidelity to God’s will in all areas of our lives is spiritual adultery toward God. That’s a hard and painful way to understand the nature of our sin, but I believe it is accurate. This lesson will help us see how we might not merely avoid marital adultery and comprehend it as harmful, but instead, the goal is to help us understand how living fully for God enables us to flourish in the abundant life to which we are called and enabled by our new life in Christ.

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