1. God made a covenant of life with Adam, whom he appointed federal head of all humanity. This was a covenant of works, under which if Adam obeyed the Lord he and all in him would live for ever and enter God's Sabbath rest. If Adam disobeyed, he and all in him would die under God's judgement. (Gen 2-3, Rom 5:12-21, 2LBC 7:1).
2. God made a covenant of grace with his elect people, who were chosen in Christ for salvation before the foundation of the world and redeemed by his blood in the fullness of time. The covenant of grace is made effective by the power of the Spirit, (Ephesians 1:3-14).
3. The Abrahamic, Mosaic and Davidic covenants were not administrations of the covenant of grace. They were 'covenants of promise' (Ephesians 2:12) in which the covenant of grace was progressively revealed 'until the full discovery thereof was completed in the New Testament' (2LBC 7:3).
4. The old covenant (the collective name for the Abrahamic, Mosaic and Davidic covenants) was not a republication of the covenant of works. The law 'was added because of transgressions, until the offspring should come to whom the promise had been made'. (Galatians 3:19). The law also served as a rule of life for Israel, setting out their covenant obligations to the Lord. In her idolatrous disobedience Israel broke the covenant and brought upon herself its terrible curses, Leviticus 26:14-39. Unlike the covenant of works with Adam, for Israel there was a way back to God from the dark paths of sin, Leviticus 26:40-45. The Lord's deliverance of his people from captivity was typical of the greater exodus accomplished by the redeeming work of Christ (Jeremiah 23:7-8, Luke 9:31, Colossians 1:12-14).
5. Abraham was the federal head of the Abrahamic covenant in whom blessing was received (Genesis 12:2-3, 17:1-8). Moses was the mediator of the Sinai covenant (Exodus 20:18-21, 33:12-17), of which David and his royal line served as federal heads. As went the king, so went the people for good or ill, (1 Kings 9:4-9).
6. While the old covenant foreshadowed the covenant of grace, it was only in the new covenant that the covenant of grace was fully enacted. (Jeremiah 31:31-34, Colossians 2:16-17, Hebrews 8, 9:15-22). Christ is both mediator and federal head of the new covenant, (1 Timothy 2:5-6, Romans 5:12-21).
7. During the Old Testament period people were saved by faith in the Christ who was yet to appear as mediator of a new and better covenant. (Hebrews 8:6, 9:15). Under the new covenant people are saved by faith in Christ who has come and accomplished the work of our redemption (Galatians 2:16, Ephesians 2:8).
8. The old covenant was with Abraham and his offspring, which is why all males descended from the patriarch were circumcised. But not all who belonged to Israel through descent from Abraham and circumcision believed and were saved (Romans 9:6, 27). Only a godly remnant knew 'circumcision of the heart' of which circumcision in the flesh was a sign (Deuteronomy 30:6, Romans 2:28-29).
9. As the historical enactment of the covenant of grace the new covenant is between God and the elect in Christ. The law is written on the hearts all new covenant people of God by the Spirit of Christ (Jeremiah 31:33, 2 Corinthians 3:3). All who believe in Jesus belong to the Israel of God, whether Jew or Gentile. Baptism is the sign that believers have been savingly united to Christ by the Spirit. (Galatians 3:27-29, 6:16). That is why according to the New Testament baptism invariably follows repentance and faith, and is linked to church membership. (Acts 2:38-39, 41-42).
10. As federal head of the new covenant, Jesus takes us not back to the beginning, but to the end of the road that Adam had to walk. (Herman Bavinck). In fact, we receive more in Christ than we ever would have had in Adam. For the riches of God's grace and the depths of his glory are only fully revealed in Jesus, the last Adam, Romans 5:21, 1 Corinthians 15:42-49, Ephesians 1:7-10, Colossians 1:27.