Genesis 1-27 tells us that God created humanity -in the image of God- and -male and female-. Every human being has been made in the image of God, and every human being is either a male or a female. But why-- What is the purpose of this sexual differentiation which defines who we are as human beings-- God's answer is found in Genesis 2-24 - humanity was designed to complement one another in the permanent bond of a relationship called marriage, which was arranged by God Himself. Marriage, then, is so much more than a 'piece of paper'. We were made, quite literally, to biologically fit together. Such is the clarity Scripture offers when we are confused.