God’s Guidelines for Sex Aren’t Arbitrary

Fair warning: This article may stir controversy. Read at your own risk. Even if there are many ways for the point I’m making here to be misconstrued or for my motives to be misjudged, I’m going for it anyway.

In a cultural moment saturated with sexual confusion, understanding the reasons behind God’s instructions about sexuality is vital—not just knowing what the Bible says but grasping why the Bible’s commands are good.

In The Gospel Way Catechism, which I wrote with Thomas West, we knew we’d need to devote one of the 50 Q&As to the question “What is sexuality?” We couldn’t imagine skipping that subject, especially when attempting to put forward biblical teaching in a way that counters the pervasive wisdom of the world.

The Why Behind the What

Today, in conversation with younger churchgoers, I find there isn’t as much debate over the Bible’s teaching on sexuality and marriage as there was 10 years ago. The controversies of the 2010s, driven by evangelical-adjacent personalities and publishers trying to muster up a case from Scripture for same-sex marriage or the moral goodness of same-sex sexual behavior, have petered out. For two reasons.

First, the loudest advocates for revisionist interpretations have continued along a theological trajectory away from orthodoxy in other areas, thereby proving marriage and sexuality to be a load-bearing wall in the house of faith. One cannot simply “agree to disagree” on the ethical issue without the underlying anthropological heresy rising up to ravage the rest of Christianity’s teaching. Tear down that wall, and other orthodox beliefs crumble around it, often with shocking speed.

Second, there’s been a proliferation of many helpful resources that lay out what the Bible teaches about sexuality. The arguments are sound—rooted in strong biblical exegesis and the unchanging witness of the church going back 2,000 years, while the tone is one of pastoral sensitivity toward people struggling with the Bible’s prohibitions in an age of confusion and distress.

Yet as I talk with young Christians, I still find a disconnect. They understand what the Bible says. They agree to submit to the Scriptures. A few can even explain a basic “natural law” understanding of the sexual complementarity required for marriage.

But many young people still struggle to explain why the biblical strictures make emotional or spiritual sense. They can’t explain why God condemns sex outside marriage as sin in a way that doesn’t sound arbitrary. It can seem as if God simply dropped these rules onto humanity, demanding compliance without explanation as to why some sexual temptations and behaviors are illicit.

I’d like to try my best to help out on this front. So, in what follows, I’m not going to expound on all the biblical restrictions around marriage and sexuality. Instead, I want to reflect on why the biblical rules aren’t arbitrary but rather line up with what the Bible teaches is good for us—body and soul—and why transgressing these commands provides a good example of the classic understanding of sin.

Sin as Curving In on Ourselves

Sin is more than doing wrong things. It is, in a view put forward by Augustine and then extended by Martin Luther, an expression of our hearts bending inward, turning away from God. The Latin phrase is incurvatus in se—a curving in on ourselves, where we grasp for God’s blessings but push away God himself. Instead of stretching upward toward the transcendent glory of God—an action that enlarges the soul, broadens our vision, and ennobles our lives—we contract into a tight little ball of self-focus, seeking fulfillment in ourselves alone.

Ironically, the heart that tries to lift itself up by its own desires ultimately debases itself. True flourishing, Augustine says, comes through the power of the Spirit in breaking the inward curve so that we’re free to reach outward and upward, finding our delight not just in the gifts of God but in God himself.

All sex outside marriage is the result of sin’s inward curving. What’s more, all sex outside marriage deepens that tendency to turn in on ourselves instead of outward in love and fruitfulness.

To be clear, even sex within the marriage covenant can betray signs of that inward curving, as it’s possible for a marriage to be marked not by self-giving love but by a husband or wife using each other for their own pleasure or withholding affection in ways that distort and shrivel the soul. But even if sex within marriage can be marred by the selfishness of sin, sex outside marriage is always, by its very nature, an expression of sin’s inward curving.

Let’s look at three examples. We’ll save the question of same-sex sexual behavior for last, because I think it’s better not to overlook the more prevalent sins among God’s people.

1. Pornography

It’s true that some still shrug at pornography, holding to a “boys will be boys” mindset (although more and more women today also fall prey to this insidious habit). But many today, even non-Christians, have awakened to porn’s soul-distorting effects. Some arrive at this conclusion from a feminist perspective—they see how pornography debases and objectifies women through degrading acts. Others see porn as a problem because it may stunt the ability of a man to “perform” in a male-female relationship.

In most church settings, when men and women seek help from other believers in overcoming this besetting sin, it’s usually because they recognize lust’s effects on their hearts and in their relationships. Perhaps they’ve experienced the downward spiral, pulled into increasingly violent or degrading scenes that would have once shocked their conscience.

As Christians, we don’t see pornography as merely “unethical” or “harmful.” We see it as a classic example of sin’s tentacles catching us and pulling us into isolation. “Sin demands to have a man by himself,” wrote Dietrich Bonhoeffer. “The more isolated a person is, the more attractive will be the power of sin over him, and the more deeply he becomes involved in it, the more disastrous is his isolation.”

Pornography is just one example of sexuality being severed from its original purpose. Even though the Bible doesn’t explicitly mention pornography, it gives us a word from which our word “porn” is derived. The Greek word porneia encompassed a wide variety of sexual sins outside marriage, and it often comes up in lists of sins. Like all sins, porneia separates us from God and the people around us. As a culture, we’ve severed sex from procreation, then severed sex from marriage, then severed sex from partnership, and now we separate sex from another person, making it all about self-gratification.

Pornography leads us into the dark shadows of shame and slowly isolates us from the people around us. In C. S. Lewis’s words, the result is “sending the man back into the prison of himself, there to keep a harem of imaginary brides. . . . No demand is made on his unselfishness, no mortification is ever imposed on his vanity. In the end, they become merely the medium through which he increasingly adores himself.” Lewis’s imagery captures Augustine’s insight perfectly: Pornography imprisons us within ourselves, narrowing our capacity for genuine love.

In pornography, the “one-flesh union” of a man and a woman becomes the “no-flesh” aloneness of a man or woman before the flickering images of a screen. Unlike Adam and Eve in Genesis 2, naked and unashamed, we’re all like Adam and Eve in Genesis 3, naked and ashamed (and hiding). No matter how bold and brash the actors may be in a pornographic video, the viewer is usually timid and ashamed, hiding behind the incognito browser or ready to swipe to another window should someone knock on the door.

Just as sin is like leprosy that deadens our ability to feel, so also with pornography there follows a deadening of the senses and the searing of the conscience. What once was sexually stirring no longer holds any power. That’s not because the person watching porn has become more alive but because they’ve become more dead. Could there be a better example of the wages of sin being death?

2. ‘Self-Abuse’

Following closely with pornography comes the question of masturbation, the point and pinnacle of watching a titillating video.

Some evangelicals—including high-profile psychologists and well-respected authors—claim that the Bible’s silence on sexual self-stimulation implies this practice must be “harmless” in adolescence unless it becomes compulsive. Since it’s a nearly universal practice among young men, they say, it must be simply part of the process of growing up, and as long as the practice can be indulged without lust, then it need not be considered sinful. We may damage the psyche of young people if we heap guilt and shame on them.

This perspective represents a radical departure from the church through the ages. We can either look at our forefathers and mothers in the faith as hypocritical, puritanical prudes whose repression required them to rule out any sexual pleasure by oneself, or we can wonder if maybe they saw something here that we don’t, something our hypersexualized culture has obscured from our view. I believe we should take the latter approach.

There’s something insightful in the name Christians gave for this practice: self-abuse. That term startles us because we generally associate abuse with physical violence or bodily coercion. But if we step into the world of our predecessors in the faith, the description begins to make sense because we start to see sexual sin as truly being against one’s own body (1 Cor. 6:18), and likewise we see the soul-shriveling aspect of sin curving inward on yourself, rewiring your brain so you become accustomed to taking what God has designed for self-giving love in union with another person and redirecting it back to yourself. It’s an example of sin’s distorting nature when you find a young man, whose virility is aimed for union with a woman, turning back on himself in self-pleasure that culminates in solitary confinement of the soul.

Some might think my naming this practice a sin, especially considering its prevalence among young people, is pastorally insensitive, or that I run the risk of loading someone down with crippling guilt or anxiety. But I don’t think the universality of a sin requires us to overlook or minimize it, just as we shouldn’t be afraid to name sins of greed or gluttony or more general lusts that constantly trip us up.

What’s more, I think most Christians know there’s something off and disordered in this act, which is why it draws shame and embarrassment. It’s an example of how sin isolates us and warps the soul, turning inward the very faculties God designed to be drawn outward. We resemble the miser enthralled with his stash of coins, or Gollum’s descent into madness due to the poisonous allure of the ring.

“The sin, if we fall into it,” wrote Lewis, “must be repented, like all our others. God will forgive. The temptation is a darn nuisance, to be born with patience as long as God wills.” Lewis sets the sin in the broader context of conquering selfishness: “Almost the main work of life is to come out of our selves, out of the little, dark prison we are all born in. The danger is that of coming to love the prison.”

3. Same-Sex Sexual Behavior

Now, let’s turn our attention to why God’s prohibition of same-sex sexual relationships isn’t arbitrary. We can come at this question from the biological perspective. Anyone can see that human bodies are designed, male and female, in complementary fashion for a sexual act ordered toward reproduction. This is why Christians continue to insist that marriage between a man and a woman is different in kind from a government-recognized “marriage” between a man and a man or a woman and woman, no matter the intensity of a couple’s affection for one another.

But the biological answer only gets us so far. Why would same-sex pairings be forbidden? Condemned as sin? Why would the apostle Paul single out same-sex sexual desire and behavior in Romans 1 as an example of God’s judgment on idolatry?

Again, let’s think of sin in terms of the human curving in on himself or herself. Whereas marriage intends to draw us out of ourselves toward the mystery of the other in self-giving love, same-sex sexual relationships draw us away from that mystery and curve back toward sameness.

It’s ironic, but one of the most insightful descriptions I’ve found about same-sex sexual desire and behavior comes from an unlikely source—Douglas Murray, a conservative gay commentator, reflecting on insights from gay classicist Daniel Mendelsohn. He wants to explain why societies have long been fascinated and unnerved by homosexuality. In the sexual union of a man and woman, he says, there’s mystery in difference, in the otherness of the beloved. The man cannot know what the woman is experiencing as a woman, and the woman cannot know what the man is experiencing as a man. In contrast, in a same-sex act the man knows both what he’s experiencing and what his partner is experiencing.

“Sex between men dissolves otherness into sameness,” writes Mendelsohn, and “since the object of that knowledge is already wholly known to each of the parties, the act is also, in a way, redundant. Perhaps it is for this reason that so many of us keep seeking repetition, as if depth were impossible.” He goes on:

He describes his same-sex sexual encounters this way: “Like falling through a reflection back into my desire, into the thing that defines me, my self.”

Mendelsohn and Murray share this insight to explain ancient and contemporary homophobia as well as the enduring cultural fascination with homosexuality, but I find here a powerful description of the curving-inward nature of sin. What better way to describe sin than a falling into ourselves, over and over again, as through a reflection, in a hall of distorted mirrors, where we’re trapped by self-desire?

All sin is disordered love—misdirected desire that aims for God and yet boomerangs back to the self in ways that stifle our love for others and squelch our fruitful capacities. Same-sex sexual behavior is just one example (out of many we could point to) of taking an act designed to draw us out of ourselves toward a great mystery and curving back inward toward the repetition and redundancy of sameness.

Gospel for Sexual Sinners

I hope it’s clear from these reflections that no one stands from a position of superiority when it comes to sexual sin. The gospel is the solution to the inward-curving selfishness of sin, no matter how that sin is expressed.

Whether it’s the young person captured by the compulsion of self-abuse, or the middle-aged woman in the shadows watching pornography for self-pleasure, or the person drawn sexually to someone of the same sex—the result is still a sinful disordering of desire that leads us further into ourselves. It leads us away from the glorious mystery of the one-flesh union that points us to the bigger, more glorious picture of Jesus and his Bride. If you find yourself in one of these portraits, please hear me clearly: My heart isn’t condemnation but an invitation into deeper freedom.

God’s rules aren’t arbitrary. Not only are his commands in line with his design (like offering a user manual for human flourishing), but they’re also in line with the glorious vision he has for transforming us more into the image of his Son. We’re aimed for a glory that draws us out of ourselves, lifts us from the pit of our disordered lusts, rescues us from self-isolation, and invites us out of the shadows of shame into the light of the self-giving love we experience from God and in God. The only way you become your true self is through the gift of yourself.

Free from the Isolating Prison of Lust

In Lewis’s The Great Divorce, there’s a ghostly man on the outskirts of heaven with a lizard of lust on his shoulder, whispering temptations into his ear. The lizard convinces the man he’s the one who supplies his happiness. A heavenly being approaches, whose blazing purity sears the man whenever he comes too close, and this angel-like figure tells the ghostly man that the lizard must die if the man is to be free. The ghostly man refuses at first, convinced any operation will kill him too. He sees himself and the lizard as too intertwined for one to live without the other. But eventually, he chooses to have the lizard killed.

The heavenly being executes the lizard in a few moments, and the ghostly man shrieks in agony. And yet once the deed is done, the man becomes magnificent, and the lizard’s corpse is transformed into a stallion. And then, Lewis writes, “the man, his face shining with tears,” leaps onto the horse’s back and “like a shooting star” they ride off into the mountains of heaven and they vanish, “bright themselves, into the rose-brightness of that everlasting morning.” The lesson, Lewis explains, is this:

Lust is always a reduction of what God intends for us. It’s never more. The young man gorging himself on pornography isn’t made stronger but weaker, his manhood not flourishing but falling into emasculation. Wherever you find yourself in this struggle, know this: What feels impossible to lose might be exactly what’s keeping you from truly living.

The good news of the gospel is that in Christ we have forgiveness, no matter how much or how often we’ve sinned in these areas. There’s no depth to which Christ will not go to rescue us. He loves us in the mud. And his rescue isn’t a mere forgiveness but a continual cleansing through ongoing repentance. He would have us walk as royals—sons and daughters of the King.

Isn’t this what we want in the process of being made more like Christ? To have the Lord untwist all that sin has twisted in us? To experience love and desire in a way that points to our ultimate goal—the union we have with Christ, the beatific vision of forever stretching further in knowledge of the triune God for all eternity, ever satisfied yet hungry for more, as we never come to the end of his wonders?

In a world soiled and sodden with sex, God’s rules intend to uncoil our selfishness until we become enflamed with divine love.

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