(Suggested resource: The Distinctiveness of Baptist Covenant Theology by Pascal Denault)
While there are a number of covenants described in the Bible (i.e., Noahic, Abrahamic, Mosaic, Davidic, etc.), Baptists believe, like paedobaptist denominations, that the Scriptures are organized around 2 main covenants: the "covenant of works" and the "covenant of grace." The distinction between us lies in a difference in understanding as to when the covenant of grace begins.
The Adamic Covenant- "the Covenant of Works"
Baptists and paedobaptists agree that God entered into a covenant of works with Adam. We find it described in Genesis 2:16-17. While it is simply a recounting of God's words to Adam, we refer to it as a covenant because it has all the marks of one:
The covenant with Adam
● Parties to the Covenant: God and Adam.
● Mediator: Adam
● Covenant community: Entire human race
● Promised blessing: Life
● Threatened curse: Death
Comparing Genesis 2:16-17 to passages such as Leviticus 18:5 we can see all the elements of a covenantal relationship are present.
The promise was life if Adam was obedient (presumably Adam, Eve and their offspring would have lived eternally in unbroken communion with God had they been obedient to God's command) but now, because of Adam's disobedience, the covenant only brings death (see Romans 5:12-21).
New Covenant Revealed (not enacted) - Genesis 3:15
This is where we depart from our paedobaptist brothers and sisters. In their system, the covenant of works was broken by Adam and the punishment due him and his progeny enacted. Upon declaring the curse, however, God enters into a "covenant of grace" with Adam in Genesis 3:15. This covenant of grace is then fleshed out and more fully revealed throughout the Old Testament. In other words, each subsequent covenant is a different administration of this covenant in Genesis 3:15, finding its fullest expression in the crucifixion and resurrection of Christ. Each covenant, along with the New Covenant, are of the same substance (grace) and the differences between them are only external and administrative factors.
The relevance for this in relation to the practice of baptism becomes immediately apparent. If the Abrahamic, Mosaic and the New Covenants are all simply different administrations of the same covenant entered into in Genesis 3:15, and infants were given the sign of being a part of the Abrahamic and Mosaic covenants (circumcision), why would they not be given the sign of being a part of the New Covenant (baptism)? You hear paedobaptists make much of the promise of Genesis 17:7 where God makes a promise to be Abraham's God and the God of his descendants after him. When the Abrahamic covenant is seen as the same as the New Covenant, then the paedobaptist takes this as a promise to him/her and giving the external sign of the covenant to their descendants is appropriate.
To the paedobaptist, baptism, like circumcision, is an external administration which is applied to all, both regenerate and non-regenerate, while grace is the internal substance which is experienced only by the regenerate. The non-regenerate benefit from being among the people of God, gaining from the blessings He pours out upon His people and by being exposed to the preaching of His word. Only the regenerate, however, reap the full benefits of the covenant of grace. The phrase "one covenant under two administrations" is a core distinction for paedobaptists. It is one covenant from Genesis to Revelation with two administrations- internal/invisible and external/visible.
Baptists, however, see Genesis 3:15 as a revealing, or promise, of the New Covenant (the covenant of grace) but not an enacting of it. In fact, Baptists do not see the New Covenant formally enacted until the coming of Christ. The authors of the Second London Confession described the New Covenant as being "revealed in the gospel; first of all to Adam in the promise of salvation by the seed of the woman, and afterwards by farther steps, until the discovery thereof was completed in the New Testament."
It could not be said to have been established until the New Testament because, as John Owen notes, "it lacked its solemn confirmation and establishment, by the blood of the only sacrifice which belonged to it. Before this was done in the death of Christ, it had not the formal nature of a covenant or a testament as our apostle proves, Heb. 9:15-23. For neither, as he shows in that place, would the law given at Sinai have been a covenant, had it not been confirmed with the blood of sacrifices. To that end the promise was not before a formal and solemn covenant."
So, where paedobaptists say "one covenant under two administrations," Baptists say "one covenant revealed progressively and concluded formally under the New Covenant." No covenant before the New Covenant was a covenant of grace but the covenant of grace remained but a promise.
In Ephesians 2:12, Paul looks back to the Old Testament covenants and refers to them as the "covenants of promise." This is exactly what Baptists argue. They were "promises" of the coming New Covenant but not the New Covenant itself. See also Hebrews 8:6, Galatians 3:17-18, and Colossians 2:17.
17th Century Baptist theologian Benjamin Keach describes the covenant of grace as going through four sequences:
1) It was first decreed in past eternity
2) It was revealed to man after the fall of Adam and Eve
3) It was executed and confirmed by Christ in his death and resurrection
4) It becomes effective for its members when they are joined to Christ through faith.
Those saved before Christ were saved because of an oath (see Heb. 6:17-18, Romans 3:25-26); those saved after Him were saved because of a covenant.
So what of the covenant(s) with Abraham?
Galatians 4:22-31 teaches that there are two posterities in Abraham: true believers and the Israelite nation, a spiritual seed and a fleshly seed. Each posterity are under different covenants represented by Hagar and Sara. Hagar, the covenant of circumcision; Sara the new covenant. Paedobaptists unite them under the same covenant of grace. (Dispensationalists, BTW, make the same mistake, giving permanent status to the physical descendants of Abraham).
The way that Baptists have seen the two covenants in Abraham is that there is one which is promised (Genesis 12) and one a formal covenant (Genesis 17).
Genesis 12 is a promise of the coming covenant. Paul, in Galatians 3:6-17, references Genesis 12 saying "the Scripture, foreseeing that God would justify the Gentiles by faith, preached the gospel beforehand to Abraham..."
The formal covenant of Genesis 17, the "covenant of circumcision," was given some 25 years after the promise of Genesis 12 and is distinct from it. The genealogical element of the covenant was only to bring forth THE Seed- Jesus. Circumcision existed to keep the lineage of Abraham going. Once that goal was accomplished, circumcision was no longer needed. As Romans 3:1-2 says, the covenant of circumcision was given to preserve the divine oracles- the promise which was not fulfilled until Christ.
Granted, it can be difficult to keep them separated as God's work to each is often the same. For example, when God freed the Israelites from Egypt, that was both a way of keeping a promise to the physical descendants of Abraham as well as picture of the spiritual liberation of the regenerate. The same act but not the same covenant, nor the same blessing or posterity.
Mosaic Covenant or "Old Covenant"
While not the same as the covenant of works made with Adam, it is a covenant of works which reaffirmed that same demand: perfect obedience. It was a progression of the covenant made with Abraham in Genesis 17. It was made with the descendants of Abraham to accomplish the promises made to him.
John Owen asked, if the covenant of grace was extant at this time, why would God create another covenant with a different nature composed of differing promises? The apostle Paul, in essence, asks this very question when he asks "Why, then, was the law given at all?" (Gal. 3:19-24).
Paul answers that the goal of the covenant was to lead us to Christ. This was accomplished in at least three ways:
1) By preserving the lineage of Abraham
2) By pointing typologically to Christ
3) By imprisoning everything under sin in order that the only means to obtain the promise was through faith in Christ.
Regarding the lineage of Abraham- God promised that the accomplishment of his promise would be fulfilled by Christ (Gal. 3:16). Consequently, the Abrahamic line needed to continue until Christ. Romans 9:4-5 teaches that Israel's privilege was to bring the promised Messiah, not to be in the covenant of grace. The point was not to establish a perpetual principle in order to include all the natural posterity of all the members of a covenant, but to lead to the ultimate posterity which is Jesus. Once that end was met, the way leading to it has come to its end. There is no physical seed beyond Christ to whom these promises are made.
The other ends for the Old Covenant was for Christ to fulfill it in order accomplish salvation for God's people.
It was this law that Christ was born under and which he fulfilled perfectly and, in doing so, reversed the curse of the covenant of works under whose curse we were all born. Samuel Petto comments: “I do not see how (by any visible dispensation) Jesus Christ could have been born actually under the law, if this Sinai covenant had not been made; for the covenant of works with the first Adam being violated, it was an end as to the promising part; it promised nothing; after once it was broken, it remained in force only as to its threatening part, it menaced death to all the sinful seed of Adam, but admitted no other into it who were without sin, either to perform the righteousness of it, or to answer the penalty; it had nothing to do with an innocent person, after broken, for it was never renewed with man again, as before: therefore, an admitting an innocent person (as Jesus Christ was) into it, must be by some kind of renewing of it, though with other intendments than at first, viz. that the guilty persons should not fulfill it for themselves, but that another, a surety, should fulfill it for them.
In this way, not only was the Old Covenant not against the promises of God (Gal. 3:21) but it was given specifically for the accomplishment of these promises (Gal. 3:22-24).
The Old Covenant was not the covenant of grace but was given because of it and in view of its accomplishment. Perhaps this is what John was pointing to in John 1:16-17.
The New Covenant
So what makes the New Covenant "new"? For (most) paedobaptists, since the substance of all the covenants are the same, the answer is simply that it is a different administration of the covenant of grace. What makes it "new" is that it is not the same administration as the Mosaic covenant. In other words, the newness is limited to the external aspects of the covenant.
Jeremiah 31 rejects this understanding. The first thing we notice in Jeremiah 31:33-34 is that the New Covenant is radically different in that it is the first formal covenant made that is unconditional. Baptists understand the New Covenant to be unconditional because the Covenant of Works was accomplished. So, the New Covenant is unconditional for all of its members, but it was not for its mediator, Jesus Christ.
Not only did the nature of the covenant make it new, but also the fact that all of its members would participate in the substance of the "Covenant of Grace" (Jer. 31:34).
The substance of the New Covenant can be summarized in 3 blessings:
1) The law written on the heart
2) The personal and saving knowledge of God
3) the forgiveness of sins
The paedobaptist see the members of the New Covenant as both regenerate and unregenerate people. They argue that the unconditional nature of the covenant is preserved because the substance of the covenant (grace) is effective to the elect, while those who participate merely in the external administration of the covenant are unregenerate. Baptists argue that this distinction is foreign to the biblical text.
Paedobaptists make a direct correlation between the sign of circumcision and the sign of baptism. Baptists deny this but they do not deny that circumcision has a New Testament corollary. Colossians 2:11-14 declares that believers are those who have received the "circumcision of Christ." This is the "putting off the body of the flesh" in order to be "raised with him through faith."
This would correlate with the "circumcision of the heart" that is called for in places like Jeremiah 4:4. God called to those who were circumcised in the flesh yet who were unregenerate. They needed to come to God through faith. Those who are members of the New Covenant, however, are those who have had this heart circumcision given to them by Christ. In other words, they are the regenerate. What is the sign that this circumcision of the heart has taken place? Baptism (Colossians 2:12).