By William M. Cwirla

You shall not commit adultery. What does this mean? We should fear and love God so that we lead a sexually pure and decent life in what we say and do, and husband and wife love and honor each other. (Small Catechism, The Sixth Commandment)

It’s time to talk like adults. Adultery is not adult behavior. It’s selfish, self-centered, and childish. But it has adult-sized consequences–biological, psychological, and spiritual.

The Sixth Commandment isn’t just about sex and “how far” you can go on a date. It’s about intimacy, commitment, covenant, and community. It’s about being man and woman created in the image of God. It’s about being a member of the Body of Christ, being redeemed by the body of Christ, and glorifying God with your body (1 Corinthians 6:12-20).

We’re Driven

Biologically speaking, humans and animals are the same. We have the same cells, the same biology, most of the same DNA. We are from the dust, and we return to the dust. But we are more than animals. We are also spiritual creatures made in the image of God. We are priests to God with dominion over the earth. We represent the Creator to the creation and vice versa.

Along with the rest of the animal world, we have a drive to reproduce. The birds do it, the bees do it, chimpanzees do it, and we do it, too–all by the impulse of the creative Word that says, “Be fruitful and multiply.” But with us, it’s different or, as they say on Facebook, “It’s complicated.” Animals reproduce; we procreate. Animals copulate; we share intimacy. The biblical phrase is “to know.” “Adam knew his wife and she conceived and bore Cain…” (Genesis 4:1). When man and woman come together sexually, they “know” and “are known” in a very unique and wonderful way. “The two become one flesh.” This is the closest kind of intimacy there is in our temporal lives, short of our eternal union with Christ and with each other as members of His body. This “one flesh” union cannot be undone by man (Matthew 19:6). It’s patterned after the union of Christ and His Bride, the church (Ephesians 5:32). And it can even occur outside of marriage (1 Corinthians 6:16)!

We build fences to keep things in, keep things out, and keep things safe. Marriage is like a covenant fence around the one flesh union of man and woman. It keeps husband and wife together, keeps others from intruding on their one flesh union, and gives them a safe place to be “naked without shame” (Genesis 2:25). Unlike with the animals, our sexual unions take place in the context of covenant, commitment, and community. “A man shall leave his father and mother and cling to his wife…” (Genesis 2:24). Marriage, intimacy, and family go together, and in that order.

We’re Commandment Breakers

Sin turns us inward toward ourselves so that we ask not “How can I please you?” but rather “What’s in it for me?” Sin perverts the Word-created desire of man for woman and woman for man into self-centered sexual lust in all its varied and perverse forms. The Small Catechism doesn’t even name them. What God made good and creative by His Word, sin makes un-good and destructive. It tears apart what God has joined together, turning desire into lust, intimacy into self-pleasure, covenant into divorce, community into isolation, life into death.

You shall not commit adultery. You shall not take God’s gift of being one flesh outside the safe confines of marriage and divorce it from covenant, community, and commitment. You shall not shack up, hook up, view porn, cheat on your husband or wife, or even think about it. That’s the way of old Adam and his lusts that bring divorce, destruction, and death. Old Adam and his lusts need to die. For this Jesus died, and from this He rescues you. You are a child of God: washed, sanctified, and justified by the Holy Spirit working through water and Word in your Baptism.

We’re Redeemed

Jesus became impure so that the impure might be pure. He became the adulterer so that the adulterer might become the virgin. Your body was redeemed in His body on the Cross. You were bought with His blood. You are a member of His Body. What you do with your body brings the whole Body of Christ with you (1 Corinthians 6:15-16). Therefore, glorify God with your body, leading a chaste, holy, and decent life in everything you say and do. And if and when God gives you a husband or a wife, love and honor him or her as “bone of your bones and flesh of your flesh” (Genesis 2:23). You are one flesh with each other. This is God’s gift to you as man and woman, husband and wife.

Rev. William M. Cwirla is the pastor of Holy Trinity Lutheran Church in Hacienda Heights, CA. He is also a president emeritus of Higher Things.

This article was originally published in the summer 2016 issue of Higher Things Magazine.