I recently stumbled upon a really useful blog, James Durham Thesis, (exploring the views of James Durham on the free offer of the gospel). James Durham summarises the gospel in 100 words:
…the general truths contained in the gospel. As, that Adam was made according to God’s image; that he fell, and broke the covenant of works … that we are by that covenant under God’s curse; that Jesus Christ the Son of God, according to the covenant of redemption, entered himself cautioner for the elect; that he really died and paid their debt; that his purchase is made offer of in the gospel; and that according to the covenant of grace, there is a real absolution from sin, and an eternal happiness to be had at the great day through embracing of him.
In an exchange of comments with the blog author, Donald MacLean, I made the following comparison between an understanding of the garden covenant as meritorious or gracious:
it [the tree of life] was so called, to hold forth to Adam sacramentaly the eternity of life, which he might expect by keeping the Covenant of Works; that tree was given him to signify and seal up that life to him, on condition of obedience.
I would differ with James Durham by rewording his statement:
it [the tree of life] was so called, to hold forth to Adam sacramentaly the eternity of life, which he might expect by keeping the Covenant of Grace; that tree was given him to signify and seal up that life to him, on condition of faith in the word of God expressed in that tree.
In other words, the tree of life functioned as a reformed sacrament, sign and seal of the thing signified (eternal life), not a Zwinglian memorial of what was promised upon condition of perfect obedience.
Had Adam exercised faith in the word of God in that tree, he would have received the superadded benefit of eternal life.
Instead, Eve and he desired, against the decretive will of God, to take and eat from the other tree and so deserved death (mot tamut – execution by royal decree).
In short, the nature of God’s covenantal offer did not alter after the fall. The garden covenant and the covenant in Christ are the same covenant which differ only by means.