Modern culture has tried to redefine sexuality as a personal right to be exercised any way an individual wishes. Sexual behavior is considered a personal choice, akin to the decision of whether to buy a house or rent a condo. At the same time, popular opinion has all but removed the word sin from our culture’s vocabulary. The only sexual expression considered “wrong” is what is deemed distasteful to the definer. However, social acceptability varies so greatly that even the vilest of acts would be considered justified by many. So, before we can determine why sexual sin is such a big deal, we have to define sexual sin.
Fortunately, man has never been given the privilege of defining sin. The One who created sexuality also has the right to set the boundaries for it, and the Bible is clear about the guidelines. When God created the first man, Adam, and brought to him the first woman, Eve, He joined them together in marriage and pronounced it “very good” (Genesis 1:31; 2:18, 24). At that time, God introduced sexuality and set the boundaries for its expression. God created a union between a husband and wife that He called “becoming one flesh” (Genesis 2:24; Matthew 19:6; Mark 10:8; Ephesians 5:31). He then defined any sexual activity outside of the husband-wife relationship as a violation of His gift. Fornication, homosexuality, pornography, and lust are all violations of God’s intent when He created the sexual act (1 Corinthians 6:9,18; Galatians 5:19-20; Jude 1:7; Matthew 5:28; Hebrews 13:4).
So why is the violation of those boundaries such a big deal? The first clue lies in Genesis 2:24 with the words “one flesh.” There is great unifying power within the sexual union. God designed it to involve not only bodies but hearts and lives. Sex was designed to consummate the lifetime union between a man and woman. Jesus said, “What God has joined together let no one separate” (Matthew 19:6; Mark 10:9). He designed male and female bodies differently so that they could come together in an act of physical intimacy that joins them together for life. They “are no longer two, but one flesh” (Mark 10:8). The act of becoming one creates a new entity: a family. This powerful force also brings forth new life (Genesis 4:25). The human race can only be propagated by the coming together of a man and a woman. And, within marriage, God blesses it (Genesis 1:28; 9:27; Psalm 17:3). Sex is a gift to a husband and wife to make their relationship unique among all other relationships.
However, what God creates as good, Satan perverts. Satan began his insidious defilement in the Garden of Eden with the words “Has God said?” (Genesis 3:1). And that challenge to the authority of God continues still. When we use sexuality for entertainment or to satisfy lust, we cheapen the beauty of this powerful gift and defy the One who designed it. We also reap the consequences of our sin. Our sexual disobedience has produced a world staggering under the weight of disease, abortion, perversion, child molestation, addiction, and sexual exploitation. God created boundaries for our good so that we could enjoy His gift as it was designed to be enjoyed.
Electricity is a powerful and helpful thing if used correctly. However, misused or abused, electricity can be deadly. The same is true of sexuality. Misused, sex is also deadly. Abusing God’s gift produces problems such as abortion, poverty, rape, adultery, divorce, and pornography. Sexual sin begins with temptation, as all sin does. When we refuse to acknowledge God’s boundaries, we allow lust to dictate our choices. And lust never leads in the right direction. James 1:13-15 says, “Let no one say when he is tempted, ‘I am being tempted by God’; for God cannot be tempted by evil, and He Himself does not tempt anyone. But each one is tempted when he is carried away and enticed by his own lust. Then when lust has conceived, it gives birth to sin; and when sin is accomplished, it brings forth death.”
Another reason sexual sin is such a big deal is that it destroys the picture of the unbreakable covenant God has with His people. The Bible uses marriage as a metaphor to describe the covenant relationship Jesus has with His “bride,” those whom He has bought with His own blood (Revelation 19:7; 2 Corinthians 11:2). In the Old Testament, God often compared rebellious Israel to a wayward wife, using adultery as a picture of the most heinous of sins (Jeremiah 3:6). God created the sex act to be a consummation of a covenant relationship—a covenant in which God has participated (Malachi 2:14; Matthew 19:6; Mark 10:9). The marriage covenant illustrates God’s unbreakable covenant with us. To engage in sex outside of marriage violates God’s intention and brings serious consequences.
Sexual sin defiles more than just our physical bodies (1 Corinthians 6:18). It has spiritual significance. Almost every book of the Bible renounces sexual immorality, indicating that God considers it a grave sin. Committing sexual sin is directly opposed to God’s will to sanctify us (1 Thessalonians 4:3).
Romans 13:13–14 outlines the life God desires us to live: “Let us behave decently, as in the daytime, not in carousing and drunkenness, not in sexual immorality and debauchery, not in dissension and jealousy. Rather, clothe yourselves with the Lord Jesus Christ, and do not think about how to gratify the desires of the flesh.” Sexual sin is one more way people gratify the flesh rather than walk in the Spirit (Galatians 5:16). Jesus said that the “pure in heart” will “see God” (Matthew 5:8). Unrepentant sexual sin defiles the heart, making it impossible to experience the power of the Holy Spirit in our lives. If we wish to be pure in heart, we cannot engage in sexual sin.