A close-up shot capturing a weathered Bible page, highlighting verses on love, forgiveness, and purity, symbolizing the Bible's guidance on matters of the heart.

What Does The Bible Say About Affairs Of The Heart?

Affairs of the heart are emotional attachments outside of marriage that can damage relationships. If you want to know what God’s Word says about guarding your heart, you’ve come to the right place.

The Bible speaks clearly about the sanctity of marriage and warns against adultery of the heart. We’ll explore relevant passages and analyze what they teach us about lust, attachment, and faithfulness in thought and deed.

Defining an Affair of the Heart


Lust can be defined as an intense desire or craving for something or someone. In the context of an affair, lust refers to sexual desire for a person who is not one’s spouse (GotQuestions). This desire is often based purely on physical attraction or fantasy and overlooks the importance of commitment, respect, and emotional connection in a marriage relationship.

Giving in to lustful desires by flirting with, pursuing romantic interactions with, or being sexually intimate with someone other than one’s spouse is considered an affair of the heart by many.

Inappropriate Emotional Attachment

An inappropriate emotional attachment refers to investing significant emotional energy, time and attention on someone other than one’s spouse. This could involve confiding secrets, discussing intimate marital details, seeking comfort, companionship or validation from another person of the opposite sex (Focus on the Family).

Such emotional intimacy is meant to be exclusive to one’s spouse and hence crossing that boundary is considered betrayal. According to statistics, as many as 25% of divorces happen due to an affair that starts as an “affair of the heart” but turns physical later (CompareCamp).

This highlights the importance of guarding one’s heart early on.

Crossing Boundaries

There are certain clear boundaries in every marriage that must be respected in order to foster trust, intimacy and faithfulness. Crossing those boundaries into emotional or physical intimacy with someone else is considered betrayal.

According to Christian views, some of the boundaries that must not be crossed outside of marriage include:

  • Flirting or being romantically interested in someone else
  • Discussing intimate marital details or frustrations with an opposite-sex friend
  • Spending significant alone-time together with someone of the opposite sex
  • Engaging in casual hugs, caresses or other physical touch with friends of the opposite sex

Infidelity does not start with the physical act alone. Most physical affairs are preceded by an emotional affair where clear boundaries are crossed (Marriage Builders). Hence it is important to guard one’s thoughts and heart by steering clear of any inappropriate intimacy or even seemingly harmless interactions that could open the door to betrayal.

As the Bible warns in Proverbs 4:23, “Guard your heart above all else, for it determines the course of your life. “

Adultery of the Heart

Matthew 5:27-28

In his Sermon on the Mount, Jesus expands the definition of adultery beyond just physical acts. He states: “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 thoughts with the act of adultery itself. He calls it “adultery of the heart.” This teaches that offenses can take place internally, even if not manifested externally.

Exodus 20:14

The commandment given to Moses states: “You shall not commit adultery” (Exodus 20:14). This forbids marital infidelity, protecting the sanctity of marriage. While the act itself is clearly prohibited, Jesus makes it clear that adultery begins internally – in the heart and mind – before manifesting physically.

So adultery of the heart violates the spirit of this commandment.

Proverbs 4:23

Solomon urges us to “Guard your heart above all else, for it determines the course of your life” (Proverbs 4:23). Our thoughts and desires shape our actions. Allowing the heart to indulge in lustful thinking can lead step-by-step down a destructive road.

Nipping adulterous thoughts in the bud is key to maintaining purity in mind and body.

The heart is central to our moral and spiritual lives. Adultery of the heart, left unchecked, violates marital commitment and can damage relationships. By expanding the definition of adultery, Jesus challenges us to take our thought-lives seriously, recognizing that purity in mind and spirit is essential for obeying God’s commands.

Guarding Your Heart

Job 31:1

In Job 31:1, Job states “I made a covenant with my eyes not to look lustfully at a young woman.” This verse highlights the importance of guarding our hearts by being careful about what we allow our eyes to see. Lustful looks can lead to sinful thoughts and actions.

Job set a high standard by making a covenant with himself to avoid lustful gazes. This shows his commitment to purity of heart. In today’s world filled with sexualized images and content, believers must be intentional about guarding their eyes and hearts.

Setting personal boundaries around media consumption and interacting with the opposite gender is wise. We must ask God to help us have pure eyes that look at others with respect rather than objectifying them.

Guarding our hearts requires making conscious efforts to avoid temptation and influences that would corrupt our minds and souls.

Proverbs 4:23-27

Proverbs 4:23-27 provides practical advice for guarding one’s heart. Verse 23 declares “Above all else, guard your heart, for everything you do flows from it.” This emphasizes the importance of protecting our hearts because our thoughts, attitudes, words and actions all originate there.

Verse 24 warns against allowing corrupt speech and perverse lips, which reveals the power of ungodly speech to defile the heart. Verse 25 encourages fixing our eyes on what is right and looking straight ahead to what is good and noble.

This promotes intentionally focusing on wholesome influences that shape the heart in positive ways. Verse 26 counsels walking straight paths and avoiding crooked ways, which speaks to living with moral integrity.

Finally, verse 27 exhorts avoiding swerving to the right or left, staying on course, and keeping our feet from evil. Overall, this passage advises being proactive about what we expose our hearts to, because our spiritual life is determined by the condition of our hearts.

Philippians 4:8

Philippians 4:8 provides an inspired filter for what kinds of things we should allow into our hearts and minds: “Finally, brothers and sisters, whatever is true, whatever is noble, whatever is right, whatever is pure, whatever is lovely, whatever is admirable—if anything is excellent or praiseworthy—think about such things.”

This verse encourages replacing negative influences with uplifting, edifying content that brings peace. Dwelling on what is excellent and praiseworthy counteracts the damaging effects of destructive input. When our minds feast on godly virtues instead of depravity, our hearts become more like Christ.

A 2014 survey of over 1,700 adults found that those who engage with inspirational media report increased happiness, meaningfulness, gratitude, and connection to others (https://www.pnas.org/doi/10.1073/pnas.1414886111).

Therefore, filtering our media choices according to Philippians 4:8 principles transforms us from the inside out.

Restoring Brokenness

Psalm 51:10

King David wrote Psalm 51 after his adultery with Bathsheba and murder of her husband Uriah. In verse 10, David cries out to God: “Create in me a clean heart, O God, and renew a steadfast spirit within me.

This verse expresses David’s deep remorse over his sin and his longing for spiritual restoration and cleansing. Though we may not have committed adultery or murder, we all need to regularly ask God to search our hearts, reveal any areas that are not pleasing to Him, and transform us (Psalm 139:23-24).

Even after being forgiven, many struggle with shame, guilt and feeling distant from God. But Scripture promises that if we confess our sins, God will forgive and cleanse us from all unrighteousness (1 John 1:9). He will give us a new, clean heart and put a new spirit within us (Ezekiel 36:26).

The Holy Spirit will empower us to experience freedom, joy and closeness with God again.

James 5:16

James 5:16 says: “Therefore confess your sins to each other and pray for each other so that you may be healed. “ This verse highlights the importance of accountability and intercession in finding healing and restoration after sin. We often try to hide our failures out of pride or fear of judgement.

However, humbly confessing our struggles to a trustworthy friend allows them to speak God’s forgiveness and truth into our lives. The prayer of a righteous person is powerful and effective (James 5:16). There is freedom and healing when sins and burdens are brought into the light (John 3:21).

Sites like Celebrate Recovery provide safe communities where people can transparently share their issues and experience healing through the love and support of others. Being vulnerable takes courage, but is so worthwhile.

We all stumble in life – we need to have grace for ourselves and others as we support one another in becoming more like Christ.

1 John 1:9

“If we confess our sins, He is faithful and just to forgive us our sins and to cleanse us from all unrighteousness.” (1 John 1:9) This promise brings tremendous hope. No matter what we have done, God is ready to forgive us completely because of Christ’s sacrifice on the cross.

As believers, our citizenship is in heaven (Philippians 3:20) – our core identity is in Jesus, not our earthly failures. God sees us as righteous, holy and blameless because we are covered by Jesus’ blood.

However, we need to keep short accounts with God and not let unconfessed sin weigh us down (Hebrews 12:1). Repentance (changing direction) and transparency with God is key to experiencing cleansing and renewal. We don’t need to vainly try to hide our struggles from the God who sees all.

He stands ready to forgive and transform us through his unlimited grace and power.


God designed marriage to be an exclusive covenant. Though we will always battle the temptation to lust, we honor Him through eyes of purity and hearts of faithfulness. If you’ve fallen into an affair of the heart, repentance and restoration are possible through Christ.

Guard your heart above all else, for it determines the course of your life.

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