The Bible is structured by architectonic principles. Reformed theologians have, by and large, agreed that all of God’s special revelation is structured by a Covenant of Works and a Covenant of Grace. This is not to say (as many have wrongly charged) that Covenant theologians do not believe in a difference between the Old and New Covenants. Neither does it mean that they do not believe that there are distinctions between the Noahic, Abrahamic, Mosaic, Davidic and New covenants. Rather, it is to say that the biblical teaching about Adam and Christ (Rom. 5:12–21) is the structuring principle of all of God’s pre-lapsarian and post-lapsarian dealings with mankind.
Prior to the fall, we were represented by Adam in the Covenant of Works. Had Adam, as federal representative, obeyed, he would have secured eternal life and holiness for all his offspring. After the fall, mankind can only be saved by God’s grace through faith in Christ, who obeyed for His people in the Covenant of Grace. The Adam/Christ structure of Scripture is what theologians have sometimes called the bi-covenantal structure of revelation.
However, insistence on a bi-covenantal structure of biblical revelation does not negate the reality of an eternal Covenant of Redemption (i.e., the pactum salutis). In fact, the better part of Reformed theologians have affirmed the existence of a pre-temporal intra-Trinitarian covenant in which the Father and the Son enter into a contract together on promises and obligations for the salvation.
The Covenant of Redemption made before the foundation of the world is based on the agreement of the Father and the Son as to the Son’s obedience, sacrifice and mediation. Some have considered such an arrangement to be distinct from the Covenant of Grace, while others have considered it to be the eternal aspect of the Covenant of Grace. What we can agree upon is the fact that before God created the world, the three persons of the Godhead entered into an agreement with one another for the plan of redemption. Read the full article by Nicholas Batzig.