In the New Testament, the word most often translated “sexual immorality” is porneia. This word is also translated as “whoredom,” “fornication,” and “idolatry.” It means “a surrendering of sexual purity,” and it is primarily used of premarital sexual relations. From this Greek word we get the English word pornography, stemming from the concept of “selling off.” Sexual immorality is the “selling off” of sexual purity and involves any type of sexual expression outside the boundaries of a biblically defined marriage relationship (Matthew 19:4–5).
The connection between sexual immorality and idolatry is best understood in the context of 1 Corinthians 6:18, which says, “Flee from sexual immorality. All other sins a man commits are outside his body, but he who sins sexually sins against his own body.” The bodies of believers are the “temple of the Holy Spirit” (1 Corinthians 6:19–20). Pagan idol worship often involved perverse and immoral sexual acts performed in the temple of a false god. When we use our physical bodies for immoral purposes, we are imitating pagan worship by profaning God’s holy temple with acts He calls detestable (1 Corinthians 6:9–11).
Biblical prohibitions against sexual immorality are often coupled with warnings against “impurity” (Romans 1:24; Galatians 5:19; Ephesians 4:19). This word in the Greek is akatharsia, which means “defiled, foul, ceremonially unfit.” It connotes actions that render a person unfit to enter God’s presence. Those who persist in unrepentant immorality and impurity cannot come into the presence of God. Jesus said, “Blessed are the pure in heart for they shall see God” (Matthew 5:8; cf. Psalm 24:3–4). It is impossible to maintain a healthy intimacy with God when our bodies and souls are given over to impurities of any kind.
Sexuality is God’s design. He alone can define the parameters for its use. The Bible is clear that sex was created to be enjoyed between one man and one woman who are in a covenant marriage until one of them dies (Matthew 19:6). Sexuality is His sacred wedding gift to human beings. Any expression of it outside those parameters constitutes abuse of God’s gift. Abuse is the use of people or things in ways they were not designed to be used. The Bible calls this sin. Adultery, premarital sex, pornography, and homosexual relations are all outside God’s design, which makes them sin.
The following are some common objections to God’s commands against sexual immorality:
1. It’s not wrong if we love each other. The Bible makes no distinction between “loving” and “unloving” sexual relations. The only biblical distinction is between married and unmarried people. Sex within marriage is blessed (Genesis 1:28); sex outside of marriage is “fornication” or “sexual immorality” (1 Corinthians 7:2–5).
2. Times have changed, and what was wrong in biblical times is no longer considered sin. Most of the passages condemning sexual immorality also include evils such as greed, lust, stealing, etc. (1 Corinthians 6:9–10; Galatians 5:19–21). We have no problem understanding that these other things are still sin. God’s character does not change with culture’s opinion (Malachi 3:6; Numbers 23:19; Hebrews 13:8).
3. We’re married in God’s eyes. This argument implies that God is cross-eyed. The fallacy of this idea is that the God who created marriage in the first place would retract His own command to accommodate what He has called sin. God declared marriage to be one man and one woman united for life (Mark 10:6–9). The Bible often uses the imagery of a wedding and a covenant marriage as a metaphor to teach spiritual truth (Matthew 22:2; Revelation 19:9). God takes marriage very seriously, and His “eyes” see immorality for what it is, regardless of how cleverly we have redefined it.
4. I can still have a good relationship with God because He understands. Proverbs 28:9 says, “If one turns away his ear from hearing the law, even his prayer is an abomination.” We fool ourselves when we think that we can stubbornly choose sin and God does not care. First John 2:3–4 contains a serious challenge for those who persist in this line of thinking: “We know that we have come to know him if we keep his commands. Whoever says, ‘I know him,’ but does not do what he commands is a liar, and the truth is not in that person.”
Hebrews 13:4 makes God’s expectation for His children crystal clear: “Let marriage be held in honor among all, and let the marriage bed be undefiled, for God will judge the sexually immoral and adulterous.” Sexual immorality is wrong. The blood of Jesus can cleanse us from every type of impurity when we repent and receive His forgiveness (1 John 1:7–9). But that cleansing means our old nature, including sexual immorality, is put to death (Romans 6:12–14; 8:13). Ephesians 5:3 says, “But among you there must not be even a hint of sexual immorality, or of any kind of impurity, or of greed, because these are improper for God’s holy people.”