[This article was taken from our book Sex and Scripture: A Biblical Study of Proper Sexual Behavior.]
The study of godly sexual behavior is not just an academic endeavor. There are few things that influence people as powerfully as the sexual drive, so it is no wonder that Satan uses it to destroy lives and negatively influence society. Sexual attraction has profoundly influenced the course of mankind, and both history and the Bible testify to this. The book of Genesis alone has many examples. Both Abraham and Isaac were afraid that they would be killed by men who wanted their beautiful wives (Gen. 12:10-20; 20:1-17; 26:7-11). Jacob was so attracted to Rachel that he served her father Laban for 14 years so he could marry her (Gen. 29:15-30). Shechem the Hivite so desired Jacob’s daughter Dinah that he talked his entire tribe into being circumcised just so he could marry her (Gen. 34:1-29). Reuben, Jacob’s oldest son, lusted after his father’s wife, and his adultery cost him his birthright (Gen. 35:22; 49:4). Joseph spent years in Pharaoh’s dungeon because a powerful woman framed him when he would not give in to her sexual advances (Gen. 39:6b-20).
The rest of the Bible and history confirm these accounts. The records of Samson and Delilah and David and Bathsheba are well known, but an intriguing and less known incident of sexual attraction is recorded in the book of Numbers. The king of Moab, an enemy of Israel, hired Balaam the prophet to curse Israel and thus destroy them. When that failed, Balaam advised the Moabites to use the lure of the sex that was a part of the Moabite worship to turn the men of Israel away from God (Num. 31:8 and 16). The tactic was successful, and “the men began to indulge in sexual immorality with Moabite women who invited them to the sacrifices to their gods” (Num. 25:1 and 2). Balaam’s strategy worked because people can be easily led away from God by sexual attraction, which can blind the eyes and blur the mind. Just as sexual attraction can lead a person away from God, it can also influence people to be godly, but godliness is achieved when the sexual drive is restrained and channeled by the force of the will to follow godly standards of behavior. Historically, sexual attraction more often than not has led to ungodliness. Understanding the powerful forces involved in the sex drive and determining what is and what is not godly behavior can be a source of blessing both to an individual and to society.
Scripture is clear that God created two different sexes: “male and female” (Gen. 1:27; 5:2; Matt. 19:4). What Scripture states, and a quick look at the difference between the male and female body substantiates, medical science is confirming more and more: there is an intrinsic difference between men and women that is much more than “skin deep.” Some people today want to “deconstruct” the traditional gender identities of male and female, saying that mankind is really “gender neutral.” These people claim that any relation or role that either man or woman feels like fulfilling is fine, because the traditional roles were established only through social evolution anyway. That is not true, and efforts to “reconstruct” men and women to be gender neutral will eventually fail. Attempts to show that the historic concept of male and female is nothing more than “social programming” demonstrate a blindness to biological and psychological facts and are fundamentally in rebellion against God and His created order. Mankind is not the product of physical and social evolution, but was created in God’s image for a magnificent purpose. 
There are people who resent Christian morals and claim they are “narrow-minded” and “religiously based,” but that argument is valid only if Christianity is a false religion. If there is a God, and if the Bible is true, then Christian morals are grounded in reality and should be adhered to in order to live healthy and fulfilling lives. There is not a shred of evidence that a “sexually free” society is more “advanced” or more “liberated” than a sexually disciplined one. Instead, the Bible warns, and history teaches, that a sexually immoral society will be one in which people are hurt and hurting. The bonds formed in sex are real, and “breakups” hurt and leave scars. Often, envy, jealousy and violence accompany “sexual freedom.” As we already said, God designed men and women differently, and what each considers “romantic,” and their approach to sex in general, differs considerably. Marriage counselors generally testify that sex and money are the two issues that couples disagree about the most. Some would add communication, but that, for the woman, is usually bundled up in the “love and relationship” category. 
For a man to really love a woman the way she needs to be loved requires selfless giving, because her needs are different than his. It is by this selfless giving that both the man and the woman become more like Christ. It is easy to see why “free sex” will never make a great society. For example, a woman having sex with a man before marriage will not help him to become like Christ, because a man offered sex without commitment will not need to discipline himself to godly principles. He will not get to the point where he considers the woman’s needs above his own sexual desires, and thousands of years of prostitutes and harems proves this very well.  Thus the woman, who needs a romantic context that includes communication and the feeling of being special, will never receive what she needs from the man and will remain unfulfilled. The “sexually free” lifestyle, while it may sound good to some, is doomed to fail. Men become more selfishly focused on what pleases them, and women, not getting the genuine love God designed them to receive, are then unfulfilled and often become hardhearted. 
Just as unrestrained sexual lust can ruin a life, so it can ruin a society. It is available to have a nation that is safe and secure, in which people are well-mannered, kind and helpful. A country can also get to the point that life is dangerous, where the “law of the jungle” is the rule and “every man is for himself.” The availability of sex without commitment hardens both men and women, and the Bible warns against it: “Do not degrade your daughter by making her a prostitute, or the land will turn to prostitution and be filled with wickedness” (Lev. 19:29). This warning certainly flies in the face of the argument that the availability of sex is somehow related to a mature society, an argument advanced by social liberals. But what Leviticus says can be clearly understood: in an environment of sex without commitment, men never learn to be giving and godly. Instead they see women as objects of their selfish desire. This, of course, leads to men not respecting women. Is this not the case today? We are living in a society where “sexual freedom” abounds. Are men more well-mannered than they were a generation ago? No, and thus we see that Leviticus is correct; there is more wickedness in a sexually free society.  It is axiomatic that the more immoral a society, the more difficult it is for an individual to be moral. Therefore, the wise person not only disciplines himself or herself sexually, but speaks up for godly rules and regulations in society.
Just as human beings are inherently sexual, they are also inherently spiritual. There is much more to us than just “flesh and electric impulses,” even if it cannot be examined under a microscope. In Scripture, God chooses to describe spiritual unfaithfulness to Him in sexual terms, such as “adultery,” “playing the harlot,” etc. Such language indicates the spiritual aspect of sex. One of the primary functions of sex is to illustrate the oneness that God intended for each of His people to have with Him, a oneness based upon our free will decisions to relinquish our right to ourselves and vulnerably open our hearts in giving worship to Him and receiving all He wants to give us. As Haffner observes:
Sex is a picture of worship that carries spiritual impact, but when it is reduced to a prosaic sport between consenting players for ego gratification and sensual pleasure, something more than archaic religious edict has been violated. Not having sex is not just maintaining moral purity for the sake of self-righteousness, and having sex is not just chipping notches on your bedpost to show how great a lover you are. Rather, sexual intercourse opens the way through an invisible, mystical veil into the spiritual realm. Within the covenantal shroud of marriage, a spirit of bonding entwines the participants and tightens the joy and depth and, yes, the feelings of belonging, and of knowing and being known, satisfying one of the greatest urges of our innermost being. 
The Bible says that when a man and woman have sexual intercourse, the two of them become “one flesh.” This is a spiritual reality that goes much deeper than the physical realm, and the Bible calls it “a profound mystery” (Eph. 5:32). Scripture clearly teaches that it is the act of sexual intercourse that makes a man and woman one flesh:
1 Corinthians 6:16
Do you not know that he who unites himself with a prostitute is one with her in body? For it is said, “The two will become one flesh.”
When a man visits a prostitute, neither one of them is looking for a relationship. They are both acting from purely selfish motives. Yet in spite of that, the spiritual reality is that they still become “one flesh.”  It is folly to deny that sex has a spiritual side to it. That spiritual element is one reason why obedience to God in sexual matters produces blessings, and why disobedience to Him can produce such bondage and suffering. Every Christian should want to obey God and receive the personal blessings that obedience brings.
While unbelievers will continue to seek to gratify “the cravings of [the] sinful nature and [follow] its desires and thoughts” (Eph. 2:3), Christians should have a different lifestyle, characterized by self control and concern for the spiritual growth of others.
 For more on this, see The Creation/Evolution Controversy, a tape seminar available from Christian Educational Services.
 Other major areas of disagreement are “who will do what” (roles in the marriage), in-laws and child rearing. The difference between the sexes and their sexual/emotional needs has been the subject of a number of books. The chapter titles in Willard Harley Jr.’s book, His Needs, Her Needs (Fleming H. Revel, Grand Rapids, MI, 1986) say a lot, and here are four: “The First Thing She Can’t Do Without—Affection,” “The First Thing He Can’t Do Without—Sexual Fulfillment,” “She Needs Him to Talk to Her—Conversation,” “He Needs Her to Be His Playmate—Recreational Companionship.”
 The difference between fiction and reality is often downplayed in movies, something Christians should expect from the secular world, which has an “anti-God” bias. The are quite a few movies portraying kind and giving prostitutes who render selfless service in all kinds of situations. Police and social workers have a different picture. Prostitutes are generally hard and harsh, which is what happens when they are nothing more than the object of men’s selfish desires.
 Some feminists are waking up to the fact that a sexually free society does not benefit women, but works instead to make men less loving, which then hurts women. The feminist Sally Cline, who refers to this sexually free period we live in as “the Genital Appropriation Era,” writes: “What the Genital Appropriation Era actually permitted was more access to women’s bodies by more men; what it actually achieved was not a great deal of liberation for women but a great deal of legitimacy for male promiscuity; what it actually passed on to women was the male fragmentation of emotion from body, and the easily internalized schism between genital sex and responsible loving.” Wendy Shalit, A Return to Modesty (The Free Press, New York, NY, 1999), p. 192.
 As society becomes “sexually free,” the respect that men have for women decreases. In a recent survey of Rhode Island teenagers who were asked if a man “has the right to have sexual intercourse with a woman without her consent,” 80% said it was okay if the couple were married; 70% if they planned to marry; 65% if they had dated for six months, 61% if they had had intercourse before, and 25% if they had taken the girl out and spent money on her. Leviticus is correct, sexual freedom leads to wickedness (survey published in A Return to Modesty, p. 40).
 Al Haffner, The High Cost of Free Love (Here’s Life Publishers, San Bernardino CA, 1989), pp. 35, 36.
 It is common to hear that a man and woman become “one flesh” as they live together and become more and more unified in their lives. Although that may be a secondary point made by the phrase, the primary point is made clear by God: it is the act of sexual intercourse that makes the two one flesh. The phrase “one flesh” is used six times in the Bible. The first is in Genesis 2:24. The other five uses are all quotations of, or direct references to, that verse. The only place the phrase is elaborated on at all is in 1 Corinthians 6:16 (quoted in the text), and it says that a man and a prostitute become “one flesh.” There is no textual evidence that the phrase “one flesh” refers to the unity achieved by the couple in marriage. This is an inference not based on what Scripture actually says.