In the covenant of grace ( is this covenant law or gospel?) God takes at least one believer and their infant into His care, promising them His grace and favor. Abraham believed the gospel BUT Abraham circumcised his infant sons (was this law or gospel?) according to God’s command (again, law or gospel?).
Both of Abraham’s sons were heirs of the covenant of grace (which one? the mosaic covenant, the Abrahamic covenant, the new covenant?), but was this by law or gospel? Though God’s freedom in election (gospel then?) was maintained and Isaac received the (gospel?) promise while Ishmael did not. So was the promise to Ishmael gospel?
Romans 9:7 “For not all who are descended from Israel belong to Israel, and not all are children of Abraham because they are his children.”
Such an example is used by the writer to the Hebrews to warn against eternal security. Of course Reformed people sometimes disagree about if these warnings are law or gospel. Are they warnings to Ishmael that he many not have ever “really” been part of the covenant but only “externally” related to “the covenant”? Or are these law warnings that many who enter the covenant are not promised they will be kept in the covenant?
Although the signs have changed, we are still in the same “the covenant” and therefore the question about if this covenant is law or gospel has not changed.
Like circumcision, water baptism is done by human hands but is represented in the New Testament not as our decision but as God’s decision and claim on Ishmael and Esau. So the question continues if this divine claim is the claim of law or gospel. Although “the covenant” obligates us to respond in faith and obedience, water baptism is God’s seal of God’s oath. So we need to find out if this oath is about law or gospel. But as long as still live, we can’t ever find out if we are Isaac or Ishmael. Both were heirs of the covenant. Both received the promises of the covenant.
In God’s act of water baptism, as in the preaching of the universal “offer”, God pledges His commitment to us in “in the covenant”. But is that commitment law or gospel? And is that commitment the same for all “in the covenant”? Of course, there are some credobaptists out there who have trouble with the idea of an ineffectual “means of grace” for Ishmael and Esau, so much so that they would rather say that water baptism is something humans do than even imply that God fails to deliver on some supposed “the covenant promise”.
This has enormous practical effects on anyone who wants to be part of the Reformed tradition. Even if it turns out that little Esau is never justified, it certainly feels good to think that Esau has been promised the same grace as Abraham has. Of course, if that grace turns out to be ineffectual in the face of human failure to meet conditions, then even Abraham might begin to wonder about the grace which has been promised to him.
It comes back to the question of law and gospel. Do we regard our children as born under the law or do we assure them they are already not under the law? Do we cling to God’s promise to work by His Spirit to keep Esau in “the covenant” in which he began, or do we have to fall back on some notion of sovereign imputation (with resulting conversion) in which every person begins life under condemnation and outside the new covenant? Even though we want to maintain God’s freedom in election (perhaps God will maintain that freedom for Himself), that is not something we really want to know about and while we do not deny it. we see no need to mention that truth when we could be emphasizing “the covenant” instead and thus maintaining the tension between law and gospel. Because that dialectic will help us to teach that ordinarily there is no salvation outside the church and its means of grace.
Of course I would not want to leave out important nuances. In my own experience, I know some credobaptists who are really in “the true church” even though of course they are still too ignorant and stubborn (which is the reason for their ignorance) to know the true marks of a true church. When water baptism is rightly understood (chiefly) as a promise made to Esau by God, then it will always be relevant to ask in retrospect if this promise was law or gospel. So what if Esau does not believe the gospel right now, certainty is always impossible, and it’s God’s decision which is still decisive, and since God promised Esau grace and claimed Esau, who is to say if that divine promise was law or gospel?
It makes a lot of difference to Esau if he was born in the covenant and is invited to the covenant table because that sacrament will be a means of grace to Esau. Unless of course, like circumcision, water baptism also often brings with it a curse! Every time I witness a water baptism today, I cling to God’s public certification that God has claimed Esau. And so while I am happy to be in the covenant, I always need to ask myself if God will cut me off if I do not keep (enough of) the law.