God’s Word is very clear about sexual immorality. Leviticus 18 illustrates how God views sexual immorality. It prohibits adultery and moves immediately in the next verse to warn against not offering one’s children to Molech, to a prohibition against male homosexuality, which the text calls an “abomination.” It prohibits bestiality (vv. 18–23). All these things made Israel unclean. The punishment for these crimes was most grave. Those punishments have expired with the expiration of the death of Christ but God has not changed. Sexual immorality is still a sin. As we have already seen, our Lord Jesus forbids sexual immorality and the Apostle Paul forbids it in both 1 Corinthians 6 and 7. Scripture is clear that homosexual behavior is a sin. The argument is sometimes made that Christian opposition to homosexuality is grounded solely in the Mosaic (Old Covenant) civil laws and thus, if Christians oppose homosexuality today, they must also seek to enforce the rest of the Mosaic civil and ceremonial legislation. If, however, there is clear teaching against homosexuality in the New Testament, that argument fails. In fact, the Mosaic civil laws in the Torah, the Pentateuch (the first five books of the Bible) were intentionally temporary and typological and the Christian view is that they were fulfilled by Christ. The New Testament opposition to homosexuality is grounded not in the Mosaic civil legislation but in nature or natural law. The New Testament arguments against homosexuality are, in that way, like its teaching on marriage and the Sabbath: they are grounded in nature, in creation, and natural law and thus existed long before the institution of the Mosaic (Old Covenant) civil and ceremonial laws and have universal application. The moral law was summarized (typologically) in the Ten Commandments (in Exodus 20 and Deuteronomy 5) and in Matthew 22:37–40, and widely throughout the New Testament.

Finally, on this topic, it has been claimed that the very concept of homosexuality did not exist until the 1860s. That claim is quite false. The ancient world, including the New Testament not only had a concept of homosexuality but a vocabulary to describe it, as will be seen below. In 1Corinthians 6:9 and 1Timothy 1:10 Paul condemns the “αρσενοκοιται” (arsenokoitai). The standard definition (Bauer, Arnt, Gingrich, Danker) is “a male who practices homosexuality, pederast, sodomite.” This is the way the word was understood in early Christian, post-canonical usage though it occurs in the same sense in the Sibylline Oracles (6th cent BC) ii.73. See Moulton and Milligan s.v.
Of course we want to avoid the etymological fallacy (deducing the meaning of a word by adding up its letters or component parts) because it does not always work and can produce misleading results but in this case it works because usage confirms what adding up the letters suggests. αρσην (arsen) = male and κοιτης (koites) = bed or euphemistically for sexual relations.

However uncomfortable it makes us late moderns, the text of 1Corinthians 6:9 is quite clear:

Or do you not know that the unjust (αδικοι) will not inherit the kingdom of God? Neither will you who deceive (πλανασθε) nor the sexually immoral (πορνοι) nor idolaters (ειδωλολατραι), nor adulterers (μοιχοι), nor the effeminate (μαλακοι), nor homosexuals (αρσενοκοιται).

I translate μαλακοι as “effeminate” because of the way it’s used in the LXX (the Greek translation of the Hebrew/Aramaic Scriptures) for the “soft parts” and is used elsewhere in the sense of “effeminate, of a catamite, a male who submits his body to unnatural lewdness, 1 Corinthians 6:9″ (BAGD, s.v.).

Paul was quite familiar with Corinth as a fairly depraved, cosmopolitan port city and he was well aware of the sorts of sexual immorality that were openly practiced there as elsewhere (e.g., Ephesus had pornographic graffiti that would make us blush). It seems clear that one thing, effeminate men who submit themselves to sexual abuse, perhaps homosexual prostitutes, led him to the last category, homosexuals.

Paul is announcing God’s judgment on several classes of sinful behaviors and warning those who commit them impenitently (without sorrow or struggle) that they must acknowledge their sin for what it is and turn to and put their trust in Jesus the Savior who obeyed and died for heterosexual and homosexual sinners and who offers free acceptance with God on the basis of faith (trust) in Jesus, the gracious Savior of helpless sinners. In HC 109 we confess

109. Does God forbid nothing more in this commandment than adultery and such gross sins?

Since both our holy body and soul are temples of this Holy Spirit, it is His will that we keep both pure and holy. Therefore, He forbids all unchaste actions, gestures, words, thoughts, desires, and whatever may entice thereto.

Purity and chastity are the opposite of sexual immorality. Our sexual behavior and attitudes, our habits, are reflections of what we love, of where we find fulfillment. The book of proverbs portrays foolishness as a prostitute because like a prostitute, foolishness promises fun and satisfaction but what it actually gives is bitterness and death.

When I was in university we watched a documentary about prostitutes in Nevada. TV and films sometimes make that life seem glamorous. It is not. It is sad, depressing, and lonely. It produces bitterness. Men were designed, by nature, when called to marriage, to give themselves to one woman. Women, who are not gifted with singleness, are intended to give themselves to one man. Sex is intended to be shrouded in trust and mutual commitment. Our culture, however, has turned that intimacy into a sad, miserable business transaction that leaves both parties hating themselves and others.

The sexual revolution has been a cruel joke. In the 1960s the sexual revolutionaries promised free sex without any commitment. What we got instead were sexually transmitted diseases and alienation. That is especially tragic since, as the Apostle Paul reminds us, the conjugal union between a man and woman is an illustration of the wonderfully intimate relationship between Christ and his church: “This mystery is profound, and I am saying that it refers to Christ and the church.” That is why sexual chastity is about more than having sex with the wrong person, it is about corrupting a creational pattern and corrupting an analogy that is meant to point to glorious spiritual mystery.

One final thought. In our culture religious and social conservatives put a lot of emphasis on heterosexual marriage. That’s understandable since the very definition of marriage as structured by nature is being revolutionized before our eyes. Courts are ruling that marriage is now to be defined as the recognition not of a natural relationship between a man and woman but as civil sanction of affection and consent.

This radical re-definition is already opening up the possibility of other, perhaps unintended consequences. The same sorts of groups who 40 years were arguing for the normalization of homosexuality are now arguing for the normalization of pederasty (sex between adults and children) and bestiality (sex between humans and animals). The argument is being made that children and animals do consent. Indeed, the most recent slide down the slippery slope is the argument that humans should be allowed to marry robots.

In all this we should not overlook the value of the single life. Paul says, in 1 Corinthians 7, that singleness is a good and valuable and that if you were single when you came to faith, and if you can stay that, you should: “To the unmarried and the widows I say that it is good for them to remain single as I am” (1 Cor 7:8; ESV). Singles are not second-class citizens in the Kingdom of God, even though sometimes they are made to feel that way in our churches. To singles I say: fulfill your vocation. Serve Christ by serving others.

To those tempted both by homosexual and heterosexual sin, you know that sexual chastity and holiness is never easy and it is particularly difficult in an age when temptation is nearby as never before but it is possible by God’s grace. You know that you have violated the seventh commandment. Confess your sins to God, turn from it, and know that he forgives you for Christ’s sake. Jesus has nailed all your sins, even your sexual sins, to the cross. God has forgiven you.

Do not become trapped in guilt. The evil one wants you to think that you can never live chastely but you can. You have been bought with a price, therefore honor God with your body, your heart, and your mind. If you are struggling with a habit, talk to someone. Confess your sin, seek forgiveness. It is good to hear the words, “You are forgiven.” Those are powerful gospel words that help keep the devil at bay.

Here are all the posts on the Heidelberg Catechism.