Contrary to dispensationalism’s sharp demarcation between God’s two peoples, Israel and the church, historic Reformed theology insists on the unity of God’s redemptive program throughout history. When Adam, the covenant head and representative of the human race, fell into sin, all human beings as his posterity became liable to condemnation and death (Rom. 5:12-21). By virtue of Adam’s sin and its implications for the entire human race, all people became subject to the curse of the law and heirs of a sinfully corrupt nature.
According to the traditional Reformed interpretation of Scripture, God initiated the covenant of grace after the fall in order to restore His chosen people to communion and fellowship with Himself. While the covenant of grace is administered diversely throughout the course of the history of redemption, it remains one in substance from the time of its formal ratification with Abraham until the coming of Christ in the fullness of time.