Today’s passage uses sayings from Paul’s day (much like the saying, “If it feels good, do it” from our day) as a spring board to talk about sex. Many people, then and now, simply see sex as an appetite. I’ve heard people say that if they get hungry, they have a hamburger; if they get horny, they have sex. What’s the difference? What’s the big deal? That’s a pretty common attitude today, even as it was in Paul’s day as well.
It’s a big deal because sex is intended by God to be more than just physical coupling, an animal act serving biological drives or physiological necessity. As verse 16 notes, in sex “two shall become one flesh.” In other words, while eating only involves the stomach (vs 13), sex involves one’s whole being. To take sex so casually that it is a mere matter of ends justifying the means is to violate the Christian view of what it means to be a person.
Second, it’s a big deal because of the kind of relationships to which Christians are called. As Christians, we have established a union with Christ which is deep and profound and touches every area of our life. To establish a union with another that is meant to be shallow and superficial in the interest of pursuing only physical pleasure is not consistent with our union with Christ. There is a lack of alignment which promotes death (death of the heart, spirit, soul) rather than life (which in its fullest sense is far more than mere material existence.)
As Christians, then, we are committed to sex only with the context a marriage, a life long union where two people become one not just in body but in heart and mind and soul, and where they don’t just treat one another as a means to an end, but love each other deeply and profoundly for the precious people they are.
It’s a high calling, to be sure. But God is surely worthy of the diligence and effort such faithfulness requires—and so is our spouse.