Often when debating the sign of baptism and whether or not infants are to be given that sign, those debating get caught up in the sign itself and leave out the covenant that necessitates the sign. My aim is to show that the New Covenant is indeed an administration of the same covenant God made with Abraham. What follows from this is that since it is the same Covenant of Grace we can expect for our children to continue to be included (especially since there is no command to no longer include them).
I want to jump right into the text here so let’s get started.
7 Know then that it is those of faith who are the sons of Abraham. 8 And the Scripture, foreseeing that God would justify[c] the Gentiles by faith, preached the gospel beforehand to Abraham, saying, “In you shall all the nations be blessed.” 9 So then, those who are of faith are blessed along with Abraham, the man of faith.
Verse 7 is one I will come back to but I will go ahead and mention now that the benefit to being a son of Abraham is that we are brought into God’s covenant with Abraham. God told Abraham in Genesis 17 that He would be God to Abraham and to his children. Being a son of Abraham is of no benefit if it does not mean that we are brought into Abraham’s covenant and reap the blessing from it. Then in verse 8 God tells us that it was indeed the gospel that was preached to Abraham. The context of “in you shall all the nations be blessed” is that it is part of God’s promise to Abraham in His covenant with Abraham. So the Abrahamic Covenant is the gospel. Already this is enough to see that the New Covenant is an administration of the same covenant given to Abraham.
10 For all who rely on works of the law are under a curse; for it is written, “Cursed be everyone who does not abide by all things written in the Book of the Law, and do them.” 11 Now it is evident that no one is justified before God by the law, for “The righteous shall live by faith.”[d] 12 But the law is not of faith, rather “The one who does them shall live by them.”13 Christ redeemed us from the curse of the law by becoming a curse for us—for it is written, “Cursed is everyone who is hanged on a tree”— 14 so that in Christ Jesus the blessing of Abraham might come to the Gentiles, so that we might receive the promised Spirit[e] through faith.
Now often times those who disagree that the Abrahamic Covenant is part of the same covenant as the New Covenant will bring up the contrast that Scripture gives us between the New Covenant and the Old Covenant. Verses 10-14 show us that it is the Mosaic Covenant (the law) rather than the Abrahamic Covenant that is contrasted with the New Covenant. In fact I challenge you to search the entire Bible where the New Covenant is mentioned and not once will you find it contrasted with the Abrahamic Covenant. Each time a contrast is made, it is made against the Mosaic Covenant.
15 To give a human example, brothers:[f] even with a man-made covenant, no one annuls it or adds to it once it has been ratified. 16 Now the promises were made to Abraham and to his offspring. It does not say, “And to offsprings,” referring to many, but referring to one, “And to your offspring,” who is Christ. 17 This is what I mean: the law, which came 430 years afterward, does not annul a covenant previously ratified by God, so as to make the promise void.18 For if the inheritance comes by the law, it no longer comes by promise; but God gave it to Abraham by a promise.
The first important thing we see here is that the Abrahamic Covenant itself is being contrasted with the Mosaic Covenant in the same way that the New Covenant is contrasted with the Mosaic Covenant. The second thing we see is that the Abrahamic Covenant was not made null and void by the Mosaic Covenant. In fact the Abrahamic Covenant was an everlasting covenant (and since it is everlasting it cannot be annulled by the coming of the New Covenant.) We see in Hebrews 7 that the Mosaic Covenant was indeed annulled by the New Covenant but the Abrahamic Covenant is never annulled and indeed it is the gospel. Because of this we know it is an administration of the same covenant. This goes back to Galatians 3:7 where we receive the inheritance of the Abrahamic Covenant (vs 18) by being sons of Abraham (which we are made sons through faith which is the New Covenant).
27 For as many of you as were baptized into Christ have put on Christ.28 There is neither Jew nor Greek, there is neither slave[g]nor free, there is no male and female, for you are all one in Christ Jesus. 29 And if you are Christ’s, then you are Abraham’s offspring, heirs according to promise.
Now this is a passage that those who hold to a Baptist view of the covenants like to use to argue that it is not physical children who are in the New Covenant but rather those who are of faith. However this notion of being spiritual children of Abraham is not new to the New Covenant at all. It has always been the case that those who are of faith are the spiritual children of Abraham. Do Baptists want to argue that in the Old Testament all of the physical children of Abraham were heirs of the spiritual promises in God’s covenant to Abraham? Scripture teaches us that there were many who were physical children of Abraham who were not true Israel at all and indeed often it was merely a small remnant who were the spiritual heirs of Abraham. Despite this all of the physical children of Abraham were included in the administration of the covenant and given the sign (for a word on the administration of the covenant versus the substance see my comment at the end of this article). It has always been that faith was required for receiving the spiritual benefits of God’s covenant with Abraham. So it is nothing new being inserted in this text here. Romans 4:11 shows us that like baptism, circumcision was a sign and seal of faith and yet there was no contradiction in God telling them to circumcise all of their physical children even though some would have no faith (11 He received the sign of circumcision as a seal of the righteousness that he had by faith while he was still uncircumcised.) Taking the context of Galatians 3 where we see so clearly that we are brought into Abraham’s covenant with God it is no problem to think that even though baptism also is a sign of faith, just like Abraham we still include our children in that covenant and give them the sign. In fact, considering we are brought into the same covenant with Abraham we would need a command from God to tell us to stop including our children and giving them the sign.
One final passage from Galatians 4 helps us wrap things up.
21 Tell me, you who desire to be under the law, do you not listen to the law? 22 For it is written that Abraham had two sons, one by a slave woman and one by a free woman.23 But the son of the slave was born according to the flesh, while the son of the free woman was born through promise.24 Now this may be interpreted allegorically: these women are two covenants. One is from Mount Sinai, bearing children for slavery; she is Hagar. 25 Now Hagar is Mount Sinai in Arabia;[e] she corresponds to the present Jerusalem, for she is in slavery with her children. 26 But the Jerusalem above is free, and she is our mother. 27 For it is written,
“Rejoice, O barren one who does not bear;
break forth and cry aloud, you who are not in labor!
For the children of the desolate one will be more
than those of the one who has a husband.”
28 Now you,[f] brothers, like Isaac, are children of promise.29 But just as at that time he who was born according to the flesh persecuted him who was born according to the Spirit, so also it is now. 30 But what does the Scripture say? “Cast out the slave woman and her son, for the son of the slave woman shall not inherit with the son of the free woman.”31 So, brothers, we are not children of the slave but of the free woman.
We see then that we, like Isaac are children of promise (keep in mind that Esau was a physical child of Isaac and yet God hated him and yet Esau was included in the administration of the covenant and was given the sign). We indeed like Isaac are brought into God’s covenant with Abraham and made heirs. One final issue that many Baptists will bring up is Jeremiah 31 where God tells us of the New Covenant. I have dealt with that argument here. In fact we see in Jeremiah 31 what I mentioned earlier and that is a contrast between the New Covenant and the Mosaic Covenant but as I said previously no contrast is made between the New Covenant and the Abrahamic. One might ask how it can be a New Covenant if it is really the older Abrahamic Covenant. It is new in 2 senses. It is new in the sense that it is a new administration (with the fulfilling of promises) of the Covenant of Grace made with Abraham. It is also new in the sense that it is a renewing of the covenant. The short explanation of this is found in the example of Moses and the people of Israel in the wilderness. When the people were faithless and God did not allow them to enter the Promised Land He made them continue to wander the wilderness. When the next generation had grown God tells them He is making a “new” covenant with them but the new covenant He makes with them is exactly the same covenant He made with their fathers. So it wasn’t an entirely new covenant but rather it was a renewing of the covenant God had previously made with them.
(A word on administration versus substance of the covenant. The short version of this is that God told Abraham to include his entire household in the covenant and sign. This did not mean his entire household had faith and was saved. So those who were included in the covenant and given the sign but did not have faith were in the administration of the covenant but did not receive the benefit of the substance of the covenant. Those who did have faith were both in the administration and the substance as they received the promise of salvation.)