A black and white photograph captures a wedding ring left abandoned on a Bible, symbolizing the pain and betrayal caused by infidelity, while reminding us of the biblical teachings on faithfulness.

What Does The Bible Say About Infidelity?

Infidelity and marital unfaithfulness are grave sins according to the Bible. God designed marriage to be an exclusive covenant between one man and one woman. Any violation of that covenant is considered adultery, which the Bible strongly condemns.

If you’re short on time, here’s a quick answer to your question: The Bible clearly prohibits adultery and describes it as a grievous sin that damages marriages and relationships. It offers warnings against infidelity and provides principles for faithfulness in marriage.

In this comprehensive article, we will examine multiple Bible passages about adultery and unfaithfulness to uncover what God’s Word says about infidelity in marriage.

The Bible’s Definition of Adultery

Adultery as Extramarital Relations

The Bible clearly defines adultery as voluntary sexual intercourse between a married person and someone other than their spouse. Exodus 20:14 states plainly, “You shall not commit adultery. “ This commandment given to Moses established from the beginning that infidelity was unacceptable and sinful behavior.

In the New Testament, Jesus reinforced this definition. He said, “But I tell you that anyone who looks at a woman lustfully has already committed adultery with her in his heart” (Matthew 5:28). Here Jesus indicates that adultery begins with the unfaithful thoughts and intentions of the heart.

Adultery of the Heart and Mind

Lust and adultery happen first inwardly before being manifested outwardly. Even sexual thoughts about someone other than your spouse are deemed morally wrong. Fantasizing about relations outside of marriage is thus considered a betrayal even if no physical contact occurs.

This spiritual standard emphasizes that in God’s eyes, both mind and actions matter greatly. Protecting the sanctity of marriage requires avoiding adulterous thoughts that can lead to sinful deeds down the road. Keeping one’s heart and conscience clear from lust is key.

Jesus’ approach goes beyond a legalistic rule-keeping concept of fidelity. The true test of faithfulness examines one’s deepest intentions and motivations. Staying committed in spirit as well as body maintains the trust and intimacy marriage is designed for.

Old Testament Verses on Adultery

The Seventh Commandment

The seventh of the Ten Commandments given to Moses by God on Mount Sinai was “You shall not commit adultery.” This commandment forbids marital infidelity and extramarital sexual relations (Exodus 20:14).

It establishes the sanctity of marriage between a man and woman, protecting the intimate bond between husband and wife.

In the Old Testament, the penalty for breaking the seventh commandment was death. Both the adulterer and adulteress were to be put to death (Leviticus 20:10). This extreme punishment showed how seriously God viewed marital unfaithfulness.

Punishments for Adultery

Under the Mosaic Law, a man who committed adultery with another’s wife was to be put to death (Deuteronomy 22:22). The woman was also to be executed if she was a consenting partner in the act. However, if the adultery took place in a town and the woman did not cry out, only the man was to be stoned to death; the woman was considered innocent (Deuteronomy 22:23-24).

One of the most well-known accounts of judgment for adultery in the Old Testament is the story of David and Bathsheba (2 Samuel 11). Though David was guilty of adultery and murder, he was spared the penalty of death because he sincerely repented before God.

Adultery in Proverbs

The Book of Proverbs contains solemn warnings against the temptation and folly of adultery:

  • “For the lips of an adulteress drip honey, and her speech is smoother than oil; but in the end she is bitter as gall, sharp as a double-edged sword” (Proverbs 5:3-4).
  • “Can a man scoop fire into his lap without his clothes being burned? Can a man walk on hot coals without his feet being scorched? So is he who sleeps with another man’s wife” (Proverbs 6:27-29).
  • “The mouth of an adulteress is a deep pit; he who is under the Lord’s wrath will fall into it” (Proverbs 22:14).

New Testament Verses on Adultery

Jesus’ Teachings on Adultery

In the Sermon on the Mount, Jesus unambiguously teaches that adultery is a sin, saying “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).

Here Jesus equates lustful intent with the act itself. He goes further to prescribe radical measures to avoid falling into sexual sin, recommending gouging out one’s eye or cutting off one’s hand if necessary (Matthew 5:29-30).

While likely figurative, this illustrates how seriously Jesus takes sexual purity.

In his famous teaching to the woman caught in adultery, Jesus shows mercy while upholding the seriousness of adultery. When the Pharisees bring a woman caught in the act of adultery to Jesus and ask if she should be stoned (the punishment under Mosaic law), Jesus replies “Let any one of you who is without sin be the first to throw a stone at her” (John 8:7).

This caused her accusers to leave one by one. But Jesus also tells the woman “Go now and leave your life of sin” (John 8:11), indicating adultery is morally wrong.

Adultery in the Epistles

The New Testament epistles uniformly condemn adultery. For example, Galatians 5 lists adultery as one of the “acts of the flesh” contrasted with the “fruit of the Spirit” (Galatians 5:19-23). Ephesians 5 instructs believers to “have nothing to do with sexual immorality” and compares allowing it into one’s life to partnering with “those who are disobedient” (Ephesians 5:7, 11).

However, the epistles also emphasize forgiveness and restoration. John’s first epistle states “If we confess our sins, he is faithful and just and will forgive us our sins and purify us from all unrighteousness” (1 John 1:9). This applies to adultery.

While a grave sin, adultery does not place one beyond God’s redemptive grace.

Principles for Faithfulness

Guard Your Heart

Staying faithful in marriage begins with guarding your heart. As Proverbs 4:23 says, “Above all else, guard your heart, for everything you do flows from it.” This means being careful about what you allow your mind to dwell on and avoiding situations that could lead to temptation.

Make a commitment to think about your spouse, not other people, when you’re faced with attractions or flirtations. Focus on developing intimacy emotionally and spiritually with your partner, not others outside the marriage.

Setting healthy boundaries with members of the opposite sex is also key. Don’t get too close to co-workers or friends of the opposite sex, especially when you’re going through a difficult time in your marriage. Seek support and companionship from same-sex friends or relatives instead.

Limit time alone with the opposite sex, and stick to public places for getting together. If you sense attraction developing, create some distance right away.

Flee from Temptation

The Bible is very clear that we need to flee from temptation and avoid situations that could lead us astray. 2 Timothy 2:22 says, “Flee the evil desires of youth and pursue righteousness, faith, love and peace, along with those who call on the Lord out of a pure heart.”

Don’t flirt with temptation or think you can indulge in a little and keep things under control. Be proactive about eliminating circumstances that could allow an affair to develop.

For example, if business travel is putting you in tempting situations, ask your employer to send a co-worker along or see if you can participate virtually. If a friendship is becoming too close for comfort, scale things back and limit contact.

Quickly cut off any sexual conversations, images, or inappropriate behavior. Recognize your weak points and take action to keep your marriage bed undefiled.

Renew Marital Intimacy

Sometimes when marriage gets stressful or routine, it’s easy to pull away from intimacy. However, God created physical intimacy between husbands and wives, so it’s important to make time for it. Having a strong sexual and emotional connection helps safeguard marriages from falling into infidelity.

Set aside time for non-sexual and sexual intimacy. Go on regular date nights together. Be affectionate in everyday ways through touches, hugs, and kind words.

If you’ve gone through a period of disconnect from your spouse, make reconnecting a priority. Try marriage counseling to work through problems. Improve your communication and really listen to each other’s needs. Pray together for unity and ask God to renew your marriage.

Affair-proofing your relationship takes time and effort, but it’s worth it!


The Bible leaves no doubt that adultery grieves God’s heart. Faithfulness in marriage is non-negotiable for followers of Christ. Through His Word, God provides clear guidance for guarding against infidelity and cultivating marital faithfulness.

His grace empowers married couples to maintain purity and fulfill their vows. If you are struggling with temptation or have committed adultery, repent and seek counsel from godly mentors. God can restore broken marriages when both spouses are committed to reconciliation.

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