The mistaken idea God doesn’t want us to enjoy the most intimate of human relationships is contradicted by the fact that God Himself was the designer and creator of the male and female bodies and declared it was all very good (Genesis 1:27-31).

From a strictly physical perspective, it seems human sexuality has been studied in every way possible. Among those who have sought to add to our understanding was Charles Darwin (1809-1882), the British naturalist famous for his theory of evolution through natural selection. Darwin spent thousands of hours studying animals and flora while postulating the implications of his studies to human beings. His ideas regarding sexual selection (the theory that competition for mates between individuals of the same gender drives the evolution of certain traits) were introduced in his first book, Origin of the Species, and even more exhaustively presented in his second book, The Descent of Man and Selection in Relation to Sex.

As a result of this and similar faulty reasoning humanity in general has overlooked the fact that human sexuality was designed much differently than animal sexuality. Darwin assumed human beings were simply part of the animal kingdom, noting that many animals typically mate with any opposite-sex member of their species that happened to be present at the appropriate time. Some have therefore mistakenly assumed it is normal and natural for people to do the same.

Sadly, this kind of reasoning has contributed to enormous ignorance about God’s purpose for human sexuality and diminished our happiness. Setting aside God’s instructions regarding human conduct, people have experimented with just about every kind of sexual relationship imaginable.

In spite of all this experimentation, research conclusively shows traditional families—where sexual relationships are only between the father and mother—produce the most successful children. As psychologist Robert Evans explains: “Children need what both fathers and mothers naturally provide. No wonder an extensive review of studies of parenting found children raised by traditionally sex-typed parents to be more competent than others” (Family Matters: How Schools Can Cope With the Crisis in Childrearing 2004, p. 49).

In the early chapters of Genesis God created each animal to reproduce “according to its kind” (Genesis 1:24-25). But when He made man, God made him in His own “image,” in His own “likeness” (verse 26). Unlike animals, human beings were modelled after God and have the opportunity to live forever, transformed into divine spirit rather than earthly matter (1 John 3:2; 1 Corinthians 15:22, 41-53).

While human beings quickly come to understand much of the physical side of sex, many have little knowledge of the emotional and spiritual dimensions that make it complete.

When God made us, there were two major spiritual principles on which we were created. The first, already noted, is that we were made in God’s image for the purpose of ultimately becoming part of His spiritual family.

The second major spiritual principle is related to our emotional intelligence and sexual conduct. In writing about marriage, the apostle Paul explained that the husband-wife relationship represents the relationship between Jesus Christ and His Church (Ephesians 5:31-32). The way Christ gave Himself for the Church is the model of conduct for husbands, and the way the Church is supposed to respond to Christ is the model of conduct for wives. God wants us to learn to control our thoughts and actions and to discover what true love really is, and marriage is the best environment given to mankind for learning these crucial spiritual principles and traits.

With this foundation, we can also have a greater appreciation for His rules for sex. When God created us both male and female, He knew we would need instruction on how to use our sexuality for good—so we could lead full, happy, complete lives. In fact, when we study the Bible, the subject of sex is one of the topics mentioned most often. God clearly explains what works best and what He had in mind for His gift of human sexuality.

Key principles about sex are found in the first two chapters of Genesis. After reading God was the Creator of sex (Genesis 1:27), we then see how it was to be used: “Therefore a man shall leave his father and mother and be joined to his wife, and they shall become one flesh. And they were both naked, the man and his wife, and were not ashamed” (Genesis 2:24-25).

From this brief overview we learn the foundational definition for a family is always one man with one woman. It is never a man with another man or a woman with another woman. In spite of human attempts to redefine family, God here establishes His intent that one man be the husband of one wife. From the Genesis 2 account we also note that the man and woman who left family to become a new family unit were to “become one flesh,” including intimacy and sexual relations (1 Corinthians 6:16).

This is the only context—with one’s spouse within marriage—in which God sanctions sexual activity. He declares sex within marriage to be holy, honorable and good (Hebrews 13:4) while forbidding all sexual activity outside of marriage—including homosexuality, group sex, bestiality, premarital sex and adultery.

While 1 Corinthians 13 is known as the “love chapter” and Hebrews 11 as the “faith chapter” Leviticus 18 is one of the best candidates for what could be call the “sex chapter.” In this passage, God gives extensive instruction regarding those with whom we should not have sex and why these prohibitions are so important.

Waiting to experience sex until one is married, and then having a sexual relationship only with one’s spouse, requires self-discipline and personal integrity. Obedience to this code of conduct is not only honorable and pleasing to God, it is a key to happy, long-lasting marriages. The benefits far outweigh the restrictions.