Few matters roil contemporary sociopolitical waters more than issues related to sex. Sex education, mandatory contraception coverage, abortion, single parenthood, same-sex marriage, divorce…the list goes on. You might think that these issues are modern, that in ancient times, the moral lines were more clearly drawn and more consistently observed.

You’d be wrong. In many ways, the first-century social world in which Christianity was born was as polymorphously perverse as our own. One writer, known to classical historians as Pseudo-Demosthenes, stated his culture’s mores this way: “Mistresses we keep for the sake of pleasure, concubines for the daily care of our persons, but wives to bear us legitimate children.” Compared to this guy, Anthony Weiner’s sexual shenanigans seem normal, and the cast of Sister Wives seems downright conservative.

One group in the ancient world stood out in stark contrast for its sexual probity: the Jews. Their critique of the Gentile world’s sexual laxity influenced the Christian view, as can be seen in 1 Thessalonians 4:3-6:

It is God’s will that you should be sanctified: that you should avoid sexual immorality; that each of you should learn to control your own body in a way that is holy and honorable, not in passionate lust like the pagans, who do not know God; and that in this matter no one should wrong or take advantage of a brother or sister.

Notice several things about this passage:

First, Paul, Silas, and Timothy frame their teaching in terms of God’s will. This is important. It means that how we use our bodies sexually is not up to us. Rather, how we use our bodies is up to God, who made us. And God desires that we be holy.

Second, holiness is not just an abstract concept, it has specific content. Negatively, we should avoid “sexual immorality.” Positively, we should use our bodies “in a way that is holy and honorable.” The missionaries’ rule sexual morality can be stated straightforwardly: chastity without marriage, fidelity within it.

Third, the practice of sexual holiness requires the development of certain habits, namely, self-control and selflessness. Faithfulness to one’s spouse over the course of their life requires a consistency of purpose and self-control that is incompatible with being swayed by “passionate lust.” It also means not using others as means to one’s selfish ends–taking advantage of others, in other words.

You’ll notice that the missionaries’ presentation of sexual morality incorporates the three elements of ethics I mentioned in a previous devotional: end, rule, and habit. For the Christian, the end of sexual activity–indeed, of all of life–is God. Our Maker is holy, and we must be too. The rule of sexual morality is both negative and positive, what to refrain from and what to engage in. And there is a habit or manner of life that makes obedience to this rule and for this end possible.

Just as the missionaries called the Thessalonians to live lives of sexual holiness in their day, they call us to do the same in our very similar age.