I have had a few discussions lately on slightly different subjects but with similar answers to the questions. I’ve discussed God’s purpose for Israel and also God’s covenant signs, along with the continuity/discontinuity between the testaments.
The common theme in the discussions was the role of Israel as God’s people and the purpose of the sign given to them. On my baptist understanding, there is one promise to which all the various covenants point (cf. Eph 2:12). Namely, the promise that God would send a messiah to redeem his people. As such, both the Old Covenant sign and the New Covenant sign point to a sure and certain promise received by faith. It is this promise of a messiah, a covenant made between God the Father and Christ the Redeemer, that is the source of salvation for all people throughout salvation history and is received by faith. In this way, we can rightly speak about a single covenant of grace.
Under the Abrahamic Covenant, the sign was circumcision. The reality of circumcision – especially where that sign is applied to your person – pointed forward to the promised seed. God promised Abraham that through him all the nations of the earth would be blessed. Scripture is clear that such blessing would ultimately be through the promised seed. Circumcision pointed to the faith belief that God would do as he promised and send a messiah to save his people.
In the New Covenant, the sign is baptism. The reality of baptism – especially how that sign is applied to your person – points to the work of God’s promised messiah. Our going down into the water symbolises our dying with Christ, our coming up symbolises our rising to new life in him and the water itself symbolises the washing from sin that we have received. Baptism points to the faith belief that our sin has been forgiven in Christ.
Both signs, then, point to one promise with an outworking in faith. The Old Covenant sign points to faith in the promised seed to come whilst the New Covenant sign points to faith in the promised messiah who has already come. Both, in essence, point us to a faith belief in Christ.
The unifying theme of the covenants is that the promise of a redeemer is linked to the way of salvation. Abraham believed God and it was counted to him as righteousness and, as Paul says, those who have faith are the children of Abraham. So the covenant people – those who are in the covenant – are those who have entered into the covenant by faith and believed God’s promise. This is true under both Old and New Covenants.
In the Old Covenant, the faith belief was that God would send a promised seed through this physical people. As such, the covenant sign marked a physical reality; namely, through Israel the promised seed would come. In the New Covenant, the faith belief is that God has sent a messiah for this people. As such, the covenant sign marks a spiritual reality; namely, for this people – drawn from every tribe, tongue and nation – the promised seed has come. The Old Covenant, then, represented a physical reality because it applied to a physical people as a sure sign that through them the messiah would come. The New Covenant represents a spiritual reality because it applies to a spiritual people as a sure sign that the messiah has come for them. Both mark a sure a certain promise, expressed by faith, to the people who receive the sign.
Throughout scripture, God gave signs of sure and certain promises. He gave a sign of a rainbow as a promise to never flood the whole earth again. He gave the sabbath as a sure and certain promise of future rest in the messiah. He gave circumcision as the sure and certain promise that the messiah would come through physical Israel. Under the New Covenant, baptism is given not as a sign of a conditional promise, but as a sign and seal of a certain reality; namely, sure salvation in Christ. This means the sign can only apply to those for whom the promise is a sure and certain reality for that is what it symbolises.
As Meredith Kline – a convinced paedobaptist – states:
This criticism leads to other major problems. Who precisely is the federal head of the children of believers: Adam or Christ? If they are unregenerate, then they are under Adam’s headship. But if they are considered ‘in the covenant of grace’, then they are under Christ. We end up with a situation in which we are simultaneously suggesting children are under Christ and Adam at the same time, in the covenant of works and the covenant of grace at the same time.
It is the baptist position that the covenant signs belong to those who are in the covenant. The New Covenant is clear that we enter into the covenant by grace alone, through faith alone, in Christ alone. Those who belong to the covenant of grace are, therefore, those whose faith is in Christ, who we can rightly call the elect. As Meredith Kline affirms, Esau was not included in the covenant because God stated he was not a child of primise. The basis for the acceptance of children cannot be the promise because the promise relates to election in Christ. The basis for receiving the covenant sign is that we are in the covenant; that is, in Christ.