A British National Health Service commuter ad is making the rounds on social media, and it seems to have offended just about everyone, though for very different reasons. The ad depicts a ladies’ stiletto high-heel shoe and a tube of lipstick on one side, and a baby’s pacifier on the other, accompanied by the grammatically irritating caption, “Would you give up this? For this?” The small print makes it clear the NHS is offering free “emergency contraception” to women “up to five days after unprotected sex.” (Whew. Baby averted.)

A few progressives are making noise over the ad because it’s apparently “outdated” and “sexist” to suggest women can’t have both high heels and children, though they are quick to praise the NHS’s “emergency contraception” services. This strikes me a little like protesting crucifixion because it kills trees.

What’s really wrong with this ad is that it treats having a baby like a fate worse than death. The clear implication of the sumptuous red lipstick and the impossibly tall high-heel is that a woman’s womb, ovaries, and breasts are recreational equipment which it would be unthinkable to waste on nurturing a new human being. Maybe when these organs are older and starting not to work so well, they can be used for making and nourishing babies—after a few rounds of chemical fertility treatment, of course. But right now, it’s party time. It’s me time. It’s little black dress time.

Because sex is fun, right? And it’s even more fun when there’s an edge of risk in it, which is why we end up with “emergency contraception” ads in the Underground and an epidemic of STDs. But what’s the purpose of all these cocktails and clubbing? Why do people devote so much of their lives to finding someone with whom to rub bodies if they’re not interested in what body-rubbing was designed to create?

Or take for example this WebMD article about “emergency contraception,” which suggests a woman might want to use it if she had sex and “something went wrong.” Could you run that by me again? In what other instance do we describe body systems accomplishing their intended functions by saying “something went wrong”? If a person ate a delicious meal and his body began to digest that meal and turn it into energy, would it not be bizarre for us to say, “something went wrong”? How do we view the ancient Romans and their fabled “vomitoriums,” where legend has it they would go to purge their first dinner so they could enjoy a second?

Nothing went wrong. If you conceived a baby after having sex, something went right. This isn’t even a moral or philosophical statement. It’s a scientific one. Two body systems, one contributed by the male and another by the female, successfully accomplished their sole biological goal. Well done, body systems. Praise God.

When people say, “something went wrong,” or they “had an accident,” or they need “emergency contraception,” I have to wonder if anyone has ever sat them down and talked about the birds and the bees. Assuming they were willingly doing the thing that makes children, you would imagine it wouldn’t come as a shock to them that they made children.

I once used an analogy that may make this a little clearer to a generation of young people who treat pets like progeny. Imagine a vending machine with a giant, red button on the front that said, “Press for Puppy.” Imagine further that people greatly enjoyed pressing this giant, red button, perhaps because it told a joke or played a little jingle when they pressed it. Then imagine that a substantial percentage of those people were shocked and dismayed when a puppy came sliding out of the chute, yipping with joy to meet its new pet-parents. Imagine that a large percentage of these new pet-parents hated this and wanted to go on pressing the button without adopting any puppies. Imagine they tampered with the workings of the machine, blocked up its entrance, started shoving devices inside, or even began killing the puppies on their way out to ensure they could keep pressing the button every weekend without opening up their own kennel club. Imagine they howled about “emergencies” and “accidents” when they heard happy barking from inside the machine, or that when a puppy did emerge, they began turning to organizations and government agencies to provide free methods of getting rid of those troublesome puppies.

I suspect any thinking person would ask, “Excuse me, if you don’t want any puppies, why on earth do you keep pressing the giant, red button that says, “Press for Puppy”?

The answer, of course, is that nothing has gone wrong when we figuratively punch the button that says, “Press for Baby” and a baby emerges. There was no accident. There was no misunderstanding. This is not an emergency. It is the miracle of life. There was a time when people understood this. If a boy got an unmarried girl pregnant, the shotgun was not far behind him, and he was not far from the altar. The link between sex and procreation was better understood because it so often dramatically changed the courses of people’s lives. But widespread contraception today has fostered the comical illusion that pregnancy is like cancer—some terrible tragedy that befalls a woman for no discernible reason. I hate to keep pointing this out but, uh, the button said, “Press for Baby.”

Of course, pressing the button is fun. But it’s not mere recreation, any more than eating is mere recreation, and attempts to make it so are as muddled as the Roman vomitorium. The NHS ad proves that sex isn’t mere recreation. If it were, then sex achieving its natural end would not be so life-changing that the government needs to chemically intervene to prevent it from happening! Sure, you may be able to keep your high-heels and lipstick, and maybe even (if you’re genetically blessed with a high metabolism) that little black dress. But when that baby arrives, you will emphatically not be able to keep the lifestyle these things symbolize: the clubbing, the hookups, the recreational pressing of the baby-button over and over with no intention of accepting what comes out the chute.

I recognize secular audiences probably won’t become chaste just because I made a cute analogy. Casual, contracepted sex is just too popular and deeply-embedded in our society. But for the sake of reason, at least stop calling it an “emergency,” an “accident,” or a “mistake” when sex does the thing it was designed to do. You’re an adult. You know what sex does. Have the decency to admit you’re deliberately breaking the machine for selfish reasons.

For those of you who do agree with me that sex belongs exclusively within marriage—for my fellow Christians—who are probably feeling a little smug right now, you’re not off the hook. I hear many of you tell me you’d like to get married so you can be with the person you love, or you’re already enjoying wedded bliss with that person but studiously keeping a contraceptive regimen because “you’re not ready for kids, yet.”

I can only repeat my earlier question to the unbelievers: Say what? You got married, knowing fully and anticipating that you would engage in sex with your spouse (indeed, you likely chose to get married with that privilege near the front of your mind), yet you are now treating it as an absolute necessity that your consummated union not fulfill one of its intended purposes?

I recognize it’s a tough world. Perhaps you do not yet have enough money to support a child. Maybe one or both of you haven’t finished school, yet. There’s a possibility neither of you may feel yourselves mature enough to be parents, yet. These are all legitimate reasons not to want kids. But if they are the reasons you’re offering, I have to ask: Why did you get married?

Let me be blunt. If you’re not financially stable enough to support children (or don’t reasonably foresee yourself being so in nine months), you’re not financially stable enough to get married. If you’re not done with school yet and consider this to be an insurmountable impediment to having children, then you should also consider it an insurmountable impediment to marriage. If you don’t think yourself mature enough to care for a child, then you’re not mature enough to have a spouse. If you’re not theoretically open to conceiving a child on your wedding night—if this blessing would be a disaster for you—then you’re not ready to have a wedding.

And if all of this strikes you as a bit of a hardship, a bit unfair, perhaps a little uncaring, ask yourself if you would say the same about my exhortations to the retching Romans or the recreational puppy-button pressers. It seems to me that if you think you can demand marriage without at least being open to children, you believe you have a right to sex. But you don’t.

Sex (and the person with whom you’re having it) are gifts from God, given under certain conditions and designed to fulfill certain ends. It’s immoral and illogical to use them for whatever ends you like merely because you have walked an aisle and said, “I do.” What you were promising (if the liturgy of your church is rooted in any way in Christian tradition) was to totally accept your spouse, including his or her potential to produce offspring. If you made those vows with mental reservations that excluded children from the picture, you didn’t make those vows on God’s terms. If conceiving a baby on your wedding night would be cause for panic, you have no right to book the reservation.

Of course, there are circumstances in which the two purposes of sex become sundered by illness or injury. Provided we are granted enough years, reproductive functions will slow and even cease for most of us. And I grant that there are times in which bringing children into this fallen world becomes financially untenable, or even medically dangerous. But in these instances, we recognize that something is wrong—something is broken—there is a barrier no couple would or at least should voluntarily impose on themselves. The exceptions do not disprove the rule, but establish it.

What the target audience of the NHS ad and voluntarily childless Christian couples have in common is a fundamentally different view of sex from God’s. Union (the joining together of spouses in a one-flesh bond) and procreation are a package deal. This much is discernible from the arrangements our Creator made in our very bodies. To chase after one and wage war on the other, whether in strangers’ beds or with our spouses, is to deny a part of ourselves. When children are seen as “emergencies” or “accidents,” the problem is with our belief systems, not our reproductive systems.