From Evidence Unseen.

Excerpt:

God created marriage to be between one man and one woman. God created us with gender (“male and female” Gen. 1:27), and he designed it so we would “leave our father and mother” (Gen. 2:24—both singular) and become “one” with our spouse. Sex outside of this context goes beyond (or against) God’s design. Jesus affirms God’s original design for sex by quoting these two passages in Matthew 19, and Paul quotes Genesis 2:24 to affirm God’s design for marriage as well (1 Cor. 6:16).

By contrast, the NT speaks against all other forms of sexuality as porneia. This is the Greek root from which we get our modern term “porn.” Paul writes about porneia often and with the strongest possible terms. Thus this isn’t simply a NT teaching, but rather, a NTemphasis:

(1 Cor. 6:13) The body is not for immorality [porneia].

(1 Cor. 6:18) Flee immorality. Every other sin that a man commits is outside the body, but the immoral man sins against his own body.

(Gal. 5:19) Now the deeds of the flesh are evident, which are: immorality, impurity, sensuality.

(Eph. 5:3) But immorality or any impurity or greed must not even be named among you, as is proper among saints.

(1 Thess. 4:3) For this is the will of God, your sanctification; that is, that you abstain from sexual immorality.

As those who know Christ, God’s will is to change us into people who have control over our sexuality, yet expressing ourselves regularly and pleasurably in marriage (1 Cor. 7:2). Resisting God’s design will depreciate your life. One author rightly said, “Nobody ever broke the law of God. You break yourself against the law of God… You don’t break the law of gravity. You break your neck.”[1] Of course, God completely forgives believers for our sins (Rom. 8:1), but he doesn’t protect us from their consequences (Gal. 6:7; Heb. 12:14-17). When we live apart from our Creator’s design, we will expect to see negative effects in our lives.

I can certainly vouch for the fact that premarital sex and especially cohabitation does enormous damage to a woman’s ability to be trusting and vulnerable. I find trust and vulnerability very attractive, but the women I know who have mashed themselves up with failed sexual relationships have a greatly diminished capacity for trust and vulnerability.

More:

Secular researchers have noted the ways in which fornication and cohabitation affect us in negative ways. Melina Bersamin (Department of Child Development—California State University) writes,

College students who had recently engaged in casual sex reported lower levels of self-esteem, life-satisfaction, and happiness compared to those students who had not had casual sex in the past 30 days… College students who had recently engaged in casual sex reported higher levels of general anxiety, social anxiety, and depression compared to college students who had not had recent casual sex.[2]

One study found that having sexual intercourse with someone only once or having sexual intercourse with someone known for less than 24 hours was significantly associated with feelings of sexual regret (Eshbaugh & Gute, 2008). Both men and women report sexual regret, albeit for different reasons, following casual sex encounters (Fisher et al., 2012). Feelings of sexual regret, and feelings of regret in general, have been linked to poor psychological out- comes, such as lower life satisfaction, loss of self-worth, depression, and physical health problems.[3]

Likewise, Robert Durant notes that “adolescents who were sexually active had significantly higher depression scores than nonsexually active subjects.” He adds that depression was “positively correlated with the number of partners in the previous 3 months.” He also points out that having a strong sense of “purpose in life” was “significantly negatively correlated with… the number of sexual partners in the previous 3 months.”[4] In other words, people that sleep around are not happier, but sadder. Moreover, people who feel that they have a purpose to their lives don’t feel the strong sense to sleep around.

It’s a question of prudence. If you want to be able to offer your future spouse trust and vulnerability, then you don’t engage in premarital sex, and especially not in cohabitation. Cohabitation basically means you give everything to a person who doesn’t commit to you. When it ends, your trust and vulnerability take a major hit, and you may never recover full function in that capacity. You basically just end up giving less of yourself the next time to the next person, and they are cheated out of the trust and vulnerability they deserve.

More studies:

Hall and Zhao (from the University of Western Ontario) studied 8,177 individuals who were ever-married. They write, “Premarital cohabitors in Canada have over twice the risk of divorce in any year of marriage when compared with noncohabitors.”[13]

Manning (et al.) writes, “Over 50% of cohabiting unions in the US, whether or not they are eventually legalized by marriage, end by separation within five years compared to roughly 20% for marriages.”[14]

Daniel Lichter and Zhenchao Qian (from Cornell University and The Ohio State University) write, “If serial cohabitors married, divorce rates were very high—more than twice as high as for women who cohabited only with their eventual husbands.”[15]

I think I know why cohabitation causes this higher risk of divorce. When a person cohabitates with another person and gives them everything (including their bodies) and the relationship fails, it makes them much more distrustful and paranoid when dealing with the next person they may like. They become unable to take the other person’s needs seriously and care for them because they are so worried about being hurt after giving up a lot to other people. If the distrustful person senses that they are holding back from the other person, they will often blame the other person for making demands on them – perhaps by imputing false motives to them, in order to justify not having to give anything back. In my experience as a chaste man, I have always felt like I was clear emotionally to give everything in each new relationship, and what I’ve found is that I have been able to easily trust each new person even after a break-up with the previous person. Break-ups don’t hurt much if you don’t get physical, and you’re more likely to stay friends with the person as well.

The really annoying thing about this is that premarital sex is so widespread that most people seem to have had it before their brains are even functioning enough to know what they really want out of life. So, instead of working backwards from the demands of marriage in order to know who to have a relationship with, they are choosing based on appearances and peer-approval far before marriage is even a possibility. By the time they get to an age where they are aware of what kind of woman or man marriage requires, they are already damaged to the point where they cannot give themselves to someone who is a good match. That’s the problem with having sex with someone when you are young – you don’t know what marriage is about, so you don’t know what to look for. It’s especially bad for women, who give away their peak sexual years (teens and 20s) to men who then want nothing to do with them. They’ve been used for sex without commitment by men who were good-looking, but not good.