When it comes to sexual behaviour, most people today assume that bibli­cal, Christian sexual ethics are at best outdated and irrele­vant, and at worst repressive and harm­ful. At best, we Christians are well-intentioned but old-fashioned prudes, who need to learn how to lighten up and enjoy life. At worst, we’re legalistic, repressed, hypocritical killjoys who spend all our time trying to stop every­one from having a good time. If we told someone that the Bible’s guidance on sexual behaviour is actually good and healthy for everyone everywhere — not just for Christians — we’d have to wait patiently for five minutes for them to stop laughing.

But this is precisely what recent secu­lar sexual research has demonstrated. Biology, psychology and sociology all support the fact that biblical sex is good and healthy.

The biblical pattern, in summary, is that sex is a good aspect of our created humanity, to be enjoyed together by one man and one woman, who have promised to be with each other for life — ­that is, lifelong, heterosexual, monoga­mous marriage. Secular research has increasingly demonstrated that both individuals and societies — Christian or not — who follow these principles tend to be healthy, happy, and wholesome, while those who don’t, tend to be unful­filled, sick, and miserable.

Helen Fisher, and her research team at Rutgers University in New Jersey, US, tracked the different chemicals that operate in the human brain during sex­ual activity. She discovered that sexual activity goes through three different phases: desire, love, and attachment. This indicates that our bodies are wired to operate best with one sexual partner for life.

Desire is a general appetite for sex — ­what we might call arousal, or “sex drive”. It is caused by the hormone testosterone operating on the limbic lobe of the brain. Sexual desire makes people do crazy things, so we sometimes think that all sexual desire is intrinsi­cally sinful and “dirty”. On the contrary, such desire is a good gift from God. In Genesis 1:28, God blessed humanity and commanded us to “be fruitful and multi­ply” — that is, have children, which involves sex. But God did not stop with the command; he constructed our bod­ies in such a way that fulfilling his com­mands would be a pleasure, not a bur­den. Sexual intercourse takes a lot of time and energy — as much energy as a kilometer’s brisk walk. It can be awk­ward and messy. If we didn’t have sex drive, we wouldn’t bother. With sexual desire, it’s a pleasure — the kind of plea­sure that Song of Songs celebrates.

Most people think that sexual desire is uncontrollable, or at least that it’s not healthy to try and control it. In contrast, recent research by Erick Jannsen and his team at the Kinsey Institute has shown that our brains are hard-wired to control our sex­ual response. His research has shown that our sexual response is controlled by two separate centres in the brain: one centre promotes sexual excitement; the other reduces it. Jannsen compares them to the pedals of a car. You speed up a car by pressing the accelerator — ­that’s like the excitation centre. The inhibitor centre is like the brake. You slow down a car by easing off the accel­erator, or by stomping on the brake. So, sexual self-control is actually possible (1 Cor. 9:25; Gal. 5:23; Titus 1:8; 2 Pet. 1:6). God wired it into us.

Jannsen’s research suggests that we can train the two centres to respond dif­ferently, through regulating what we feed into our brain. If we feed our brains with pornography, prostitution, and fringe sexual practices, we will become more and more dependent upon them, and will respond less and less to our spouse. If, in contrast, we fill our mind with our spouse — by spending time with them, doing fun and exciting things with them, and communicating with them and deliberately avoid pornography, prostitution, and fringe sexual practices, then we will be more and more attracted to our spouse, and less and less attracted to the other things. We will have trained our accelerator and brake to operate in favour of our spouse, and against other forms of sexual desire. Or, to put it another way, we must renew our minds (Rom. 12:2; Gal. 5:16-17; Eph. 4:17-24). “Whatever is true, whatever is noble, whatever is right, whatever is pure, whatever is lovely, whatever is admirable, if anything is excellent or praiseworthy, think about such things” (Phil. 4:8); “Set your minds on things above, not on earthly things” (Col. 3:2).

So far, we have only discussed sexual desire. Such desire is not focused on one person. It can be satisfied by any­thing — sex with your own wife or hus­band, sex with someone else’s wife or husband, pornography, etc.

But Helen Fisher’s research shows that sexual desire is also associated with different chemicals in our brain, which move us on to the second phase of sex­ual activity: love. Falling in love is spe­cific: it is focused on one person. These intense, romantic feelings are caused by another hormone, Dopamine, affecting parts of the brain which neurologists call the “reward system”. Brain scans have shown those parts of the brain lighting up when a person is in love. Biologists call dopamine the “feel good” chemical. Whenever we’re with the per­son we love, or we think about them, dopamine is produced and sprayed to all parts of our brain, giving us an emo­tional high.

Desire and love can be separated, but should not be. Fisher’s research found that biologically, they happen together. Sex was never meant to be merely “recreational”. Recreational sex is a recent phenomenon where people have sex with each other “just for fun”, with­out any personal commitment. They don’t even have to know each other’s names. It reduces sexual partners to toys: after we finish playing with each other, we throw each other away. God’s pattern for sexuality, which is supported and affirmed by our biological func­tions, is for sex to be a deeply personal act which unites people at an emotional level. They are to become one flesh, unashamedly naked before each other (Gen. 2:24-25).

Fisher’s research also shows us that when we have lots of sex with one per­son, we get so deeply connected with them, that we want to stay with them. This is the third phase of sexual activity: attachment. Sexual activity releases the hormones oxytocin and prolactin in our brains. Biologists call these the “cuddle hormones”: they make us feel a deep union with the person we’re having sex with. So, the more sex we have with someone, the closer we bond emotion­ally with them.

So, biologically, we are wired to desire sex; to fall in love with the person we desire sex with; and for that love to develop into a deep attachment. Our bodies are wired to operate best with one sexual partner for life.

So far, we haven’t established that this sexual partner needs to be of the opposite sex. Everything we’ve said so far could apply to homosexual sexual activity. But this ignores the simple, biological fact that our bodies are wired to have sex with the opposite gender, not the same gender. Male and female sexual organs are compatible — they fit together, and work together well. When a man and woman have sex with each other, they give each other great joy and pleasure, and they bring new life into the world. Only heterosexual sex makes babies.

In contrast, homosexual sexual activ­ity forces the body to do things it wasn’t designed to do. Therefore, not only does it prevent new life, it causes injury and spreads disease. The Lesbian-Gay-Bisexual-Transgender health web­site itself warns that “anal cancer affects men and women, but it is the only can­cer with a greater prevalence among men who have sex with men (MSM) than in the general population. About 35 in every 100,000 MSM develop anal cancer, compared to less than one in every 100,000 heterosexual men”.

Our bodies are wired to operate with one sexual partner, of the opposite gen­der, for life — which is exactly the biblical pattern.

So, it’s no surprise that sociological research shows us that people who live according to this pattern tend to be healthy and happy, and people who break this pattern tend to be unfulfilled and miserable. People in healthy marriages have greater life satisfaction, and lower blood pressure, stress, and depres­sion, than single people. Children grow­ing up in single-mother or grandparent-only families tend to have poorer mental and physical health than children living with their two biological parents.

The US Government’s Healthy Marriage Initiative reports that men, women and children who are members of healthy families are, among other things, emotionally and physically healthier; less likely to abuse drugs or alcohol; and have better relationships with each other. The children are more likely to succeed academically; the men are less likely to commit violent crimes; and the women are less likely to be vic­tims of domestic violence, sexual assault, or other forms of violence. A loving marriage makes a person as con­tent as an extra annual income of $140,000.

In contrast:

family fragmentation costs US taxpayers at least $112 billion each and every year, or more than $1 tril­lion each decade ... These costs arise from increased taxpayer expenditures for anti-poverty, criminal justice, and education programs, and through lower levels of taxes paid by individuals who, as adults, earn less because of reduced opportunities as a result of having been more likely to grow up in poverty ... If, as research suggests is likely, marriage has additional benefits to children, adults, and communities, and if those benefits are in areas other than increased income levels, then the actual taxpayer costs of divorce and unwed childbearing are likely much higher.

One side effect of the recent culture of “casual” or “recreational” sex among young people has been a sudden increase in sexually transmissible infec­tions (“STIs”), including chlamydia, gonorrhea, HPV, herpes, syphilis and HIV/AIDS. There were around 70,000 reported cases of STIs in Australia in 2008 — 13% more than in 2007. Three quarters of known cases occur among people aged between 15 and 29 years. That’s frightening, because many of these STIs have no symptoms, but can make women infertile. The Australian government is so concerned that they ran a national advertising campaign in 2009. You might have seen the bill­boards, which say “you could have it, and not even know”.

Biblical, Christian sexual behaviour is not outdated, repressive or harmful. It is, in fact, healthy and life-affirming, because it agrees with the way our good God designed us as human beings, and the patterns He teaches us in His Holy Word. Modern-day sexual behaviours, which reject these patterns in the name of “freedom” — actually self-obsessed irresponsibility — are dangerous and unhealthy. Secular research proves it. We can unashamedly make a stand for biblical, Christian sexual behaviour, confident that what we say is biblically true, and good and healthy for every­one.