What is the purpose of sex in marriage? What is God’s design? I want to suggest three reasons clearly revealed in Scripture. First, the most obvious: procreation. It is God’s design to provide a safe haven in which to rear children. A second purpose is companionship. Sex is a bonding experience. The biblical phraseology is, “The two become one flesh.” It is deep, deep companionship. I believe this is why sex is reserved for marriage. It is our unique expression that we are one. The third reason for sex in marriage is for pleasure. If you doubt this, read Song of Solomon. God’s design was mutual sexual pleasure.