It had always been known that salvation would come to the gentiles, because it had been promised to Abraham that in him all nations would be blessed. Because Abraham is the father of the Jewish nation, it was put forth by the Judaizers that the gentile Galatians could be saved only by their becoming Jews. The reasoning was that, because the Jews point to Abraham as their father, and the gentiles would be blessed through him, the blessing could occur only if the gentiles became Jews. By identifying with God through circumcision, which God had given Abraham, they would become Jews and be subject to the Law of Moses, just as Jews.
The logic of the men from James seemed impeccable and could be argued from the Scriptures, but Paul saw a fault in their logic and had a more authoritative Scriptural argument than the legalists. Paul’s second argument showing our salvation is through faith alone comes from the experience of Abraham and is presented in Galatians 3:6-9. Here he shows that the father of the Jewish race is the father of faith, and, as such, is the father of the faithful, whether Jew or gentile. Paul begins by showing how Abraham was accounted righteous. This is important, because the men from James preached that righteousness comes through obedience to the Law of Moses. Nevertheless, Abraham was found righteous according to Galatians 3:6 (cf. Romans 4:1-5, 22-25), because he believed God. That is, Abraham’s righteousness came through his faith in God.
According to Genesis 15:6, Abraham believed God, when God told him that his descendants would be as innumerable as the stars of heaven. The ancients considered that their lives were extended through their descendants. The problem was that Abraham perceived his life was at an end, because he couldn’t provide the child for the Lord to bless (Genesis 15:2). No matter how hard Abraham tried, he was unable to extend his life through his descendants, so he thought God’s promised blessing was simply out of his reach. However, when God told Abraham that Abraham’s descendants were God’s responsibility (Genesis 15:4), Abraham trusted God to give him the descendants he promised and thereby extend his life.
One may say, “Okay, this is fine, but how does faith make us a child of Abraham” (Galatians 3:7)? Well, we could also ask: “What sort of power do we have to continue our lives?” Are we, through our own power, able to lengthen our lives by a single day (Matthew 6:27)? Obviously, we have no such power, and, like Abraham, we need to trust God to extend our lives as he promised to do. Therefore, since Abraham was the first who trusted God in this manner, he is the one we all look to for our example. God was faithful to faithful Abraham and extended his life through his descendants. We can, therefore, trust that God will be faithful to us as well.
In giving us Abraham’s experience as our example, Paul shows the weakness of the Law. The Scripture concludes that everyone whether he keeps the law or not (Romans 2:12) is unable to add a single day to his life (Genesis 15:2; compare Romans 8:3). This is even more certain, since the Scripture also concludes that all of us have broken the Law (Romans 3:23). Therefore, the Law is powerless to add to our lives. On the contrary, because of transgression it demands our lives.
The most important link to Abraham, therefore, is not through genetics or the work of building a family but through faith (Genesis 15:5-6; John 1:12; 3:16). As Abraham’s spiritual sons, we are completely dependent upon God for eternal life. Nevertheless, how do we know that, in the same manner Abraham was accounted righteous (Genesis 15:6), gentiles are also considered righteous? If gentiles had to become Jews in order to be saved, which is what the Judaizers were preaching, then their argument contradicts God’s promise to Abraham. God told Abraham that all nations would be blessed in him. Therefore, if all gentiles (or nations), had to become members of the Jewish nation in order to be saved, as the Judaizers preached, then their gospel claimed that only one nation was blessed in Abraham. This contradicted God’s word, and cannot be true (John 10:35).