Human beings have practiced sexual sin since the very beginning, but for many centuries in the West, sexual sins were met with public disapproval. Since at least the 1960s, however, Western culture has increasingly accepted a sexual ethic in which nearly everything goes. Sex between unmarried people, premarital cohabitation, homosexuality, and a host of other practices today enjoy widespread societal approval.
This is not the first time that Christians have lived in a society that tolerates and even promotes sexual decadence. The first-century Greco-Roman world, where the first Christian churches were planted, was filled with sexual license. Homosexual behavior was widely tolerated. It was customary for pagan husbands to have mistresses and to use female slaves to satisfy their sexual desires. Prostitution was rampant, and there were even forms of pornography in that era’s art and literature.
When people converted to Christ, however, they were expected to put away all these things. As we see in today’s passage, the will of God for His people is their sanctification, which includes abstinence from “sexual immorality” (1 Thess. 4:3). The Greek word translated as “sexual immorality” (porneia) refers to all sexual activity outside of the one-man/one-woman marriage covenant. Christianity adopted the ancient Jewish sexual ethic, which is not surprising since that ethic comes from the Old Testament. Consequently, sexual activity is reserved for the one place God has ordained it—the one-flesh marriage bond (Gen. 2:24). Thus, homosexual activity, bestiality, premarital sex, adultery, polygamy, and other sexual behaviors that occur outside of monogamous heterosexual marriage are forbidden to God’s people. And since Jesus makes it clear that sexual sin extends even to our desires (Matt. 5:27–30), lusts that are never realized with another creature are also forbidden. This makes the mere desires for things that are forbidden by God sinful as well.
Christians are not to be controlled by their sexual desires; rather, we are to practice self-control and abstain from all forbidden sexual activity, whether in thought, word, or deed (1 Thess. 4:4–5). Any professing believer who claims otherwise is in grave spiritual peril. The gospel sets us free from sin to honor God with our minds and bodies, so believers will seek to bring their sexual activities and desires into conformity with our Creator’s Word.