When the church confesses the necessity of the satisfaction of God’s righteousness, this necessity is not something that is imposed upon God from the outside, but it is a necessity imposed upon God by His own character and nature. It is necessary for God to be God, never to compromise His own holiness, righteousness, or justice. It is in this sense that an atonement that satisfied His righteousness is deemed necessary.
In the eleventh century, one of the church’s most brilliant thinkers, Anselm, archbishop of Canterbury, wrote three important works that have influenced the church ever since. In the field of Christian philosophy, he gave us his Monologium and his Proslogium; in the field of systematic theology, he penned the great Christian classic Cur Deus Homo, which being translated means “Why the God-Man?”
In this work, Anselm set forth the philosophical and theological foundations for an important aspect of the church’s understanding of the atonement of Christ, specifically the satisfaction view of the atonement. In it, Anselm argued that it was necessary for the atonement to take place in order to satisfy the justice of God. That viewpoint became the centerpiece of classical Christian orthodoxy in the Middle Ages, in terms of the church’s understanding of the work of Christ in His atonement. Since then, however, the satisfaction view of the atonement has not been without its critics.
In the Middle Ages, questions were raised about the propriety of thinking that the atonement of Jesus was made necessary by some abstract law of the universe that required God’s justice to be satisfied. This gave rise to the so-called Ex Lex debate. In the Ex Lex debate, the question was raised as to whether God’s will functioned apart from any law or outside of any law (ex lex), or whether the will of God was itself subjected to some norm of righteousness or cosmic law that God was required to follow and, therefore, His will was exercised under law (sub lego). The question was: Is God apart from law or is He under law?