In making the New Covenant—once we have proceeded through the process of repentance and baptism, and have received God's Spirit—which baptizes us into Christ—we are then Abraham's children. That is, we are Abraham's descendants regardless of our race, regardless of our national origin. We are therefore part of that one Family into which God is drawing all of mankind, and we are made heirs of the promises made to Abraham as part of the Abrahamic Covenant. All the Old Covenant did was bridge the gap from the time Israel was released from their bondage until the promised Seed came.
Abraham was concerned that he had no children. In this section, God promised him that he would have countless children. Into this comes faith. Abraham believed Him. It is that simple. When it says that Abraham believed, we can understand from other portions of the Bible that his belief was such that it motivated him to submit—to obey God.
The word can also be translated "mature." It can also be translated "complete." It sounds to me like it is very similar to what God said to Abraham. What is Jesus beginning to do? He is beginning to introduce concepts that are part and parcel of both the Abrahamic Covenant and will also be part and parcel of the New Covenant.
Now, Abraham is very plainly called "the father of the faithful." It is as though he is the head of the family. It is as though as the head of that family, he, of all who have ever lived, with the exception of Jesus Christ, is the model after which we are to mold ourselves.
We also saw (back in Galatians 3) that, if you are Christ's, you are Abraham's seed and heirs according to the promise. Things are beginning to come together here within God's purpose, and they are coming together within the church.
Now we see that Abraham passed the test. What did he do? Abraham upheld his end of the covenant. Because that Abraham obeyed My voice, and kept My charge, My commandments, My statutes, and My laws.
I have kind of gone way around the pole, you might say, in order to impress upon you the fact that under the New Covenant the promises of the Abrahamic Covenant are valid and that Abraham is our spiritual father, as it were. He is the model of the family. And the model of the family, with whom God first made the covenant, obeyed God's voice. He kept God's charge. He kept the commandments and he kept the laws and Abraham's children are going to do the same thing! Otherwise, they will not show the characteristics of Abraham; and they will not really be his children.
Paul is not doing away with laws in the book of Galatians! He is simply saying law keeping cannot justify us. It is that simple. Sometimes we have to go way around the pole in order to get to the root of things. We see here, by God's own witness that Abraham lived up to the terms of the covenant. And because he did, it was being passed on to Isaac for him to do as his father, Abraham, had done.
But the problem of transgressions to the terms of the Old Covenant was not resolved until the promised Seed, Christ, came. When He came, He lived perfectly. He qualified to be the payment for sin and, at the same time, He confirmed the promises that were made unto Abraham—and they were made absolutely, eternally binding. God then proposed the New Covenant that He had previously prophesied of (in Jeremiah 31), which ties everything into one neat package. And He has presented it to all of mankind—not just Abraham's physical descendants.
It is not circumcision which makes one a part of this covenant. That was the sign that was given to Abraham and his physical descendants. Rather, it is circumcision of the heart! It is repentance and faith in the sacrifice of the promised Seed (Jesus Christ) that is the sign; and the receipt of the Holy Spirit is the seal. It authenticates what has occurred. It completes the making of the New Covenant with the individuals that God is calling.
. . .
