Rather than viewing marriage as a public matter, many people today see it strictly as the domain of two consenting persons. For the foundation of marriage, these people look solely to the private, inward commitment of a man and a woman who are in love. And where such commitment is present, proponents quickly add, the expression of this commitment through the sex act is entirely appropriate. As Christians, we would readily agree that the inward commitment of a man and a woman to be spouse to each other is central to a God-honouring marriage. This New Testament understanding has its roots in the Old Testament.
Inward commitment does form the basis of marriage.
But the Bible also points out that in every area of life genuine commitment cannot stand alone. Rather, true inward commitment naturally comes to outward expression. James, for example, speaks about faith thus. In the same way, faith by itself, if it is not accompanied by action, is dead. . . In the same way, the inward commitment of two persons for each other ought to find its proper outward expression.