In Galatians 3:7, Paul, writing to Gentiles, says, “Know then that it is those of faith who are the sons of Abraham” (ESV). Here Paul advances the idea of a spiritual family in contrast to a physical family—a family sharing faith rather than a bloodline.
Obviously, Abraham had literal, physical descendants. It was they, through Isaac and Jacob, who became the nation of Israel, God’s chosen people. However, many in Israel did not follow God the way that they should have. At the same time, there were some Gentiles in the Old Testament, like Rahab and Ruth, who were adopted into the family of Israel. In the New Testament, many Gentiles are “grafted” into the tree of Israel through their faith in Jesus, the Messiah of Israel (Romans 11:17–20).
Throughout the New Testament, we see that being physical descendants of Abraham, although culturally important, counts nothing for eternity. When John the Baptist was preaching to the Jews, he warned, “Do not think you can say to yourselves, ‘We have Abraham as our father.’ I tell you that out of these stones God can raise up children for Abraham” (Matthew 3:9). John’s point was that more important than their physical lineage was their spiritual lineage.
In John 8:32–41, Jesus is speaking to some Israelites who were by definition descendants of Abraham. However, Jesus says that their physical lineage is overshadowed by their negative spiritual lineage:
[Jesus said] “Then you will know the truth, and the truth will set you free.”
“They answered him, “We are Abraham’s descendants and have never been slaves of anyone. How can you say that we shall be set free?”
Jesus replied, “Very truly I tell you, everyone who sins is a slave to sin. Now a slave has no permanent place in the family, but a son belongs to it forever. So if the Son sets you free, you will be free indeed. I know that you are Abraham’s descendants. Yet you are looking for a way to kill me, because you have no room for my word. I am telling you what I have seen in the Father’s presence, and you are doing what you have heard from your father.”
“Abraham is our father,” they answered.
“If you were Abraham’s children,” said Jesus, “then you would do what Abraham did. As it is, you are looking for a way to kill me, a man who has told you the truth that I heard from God. Abraham did not do such things. You are doing the works of your own father.”
Twice, Jesus agrees that they are Abraham’s children but implies they really have another father. In verse 44 He states it plainly: “You are of your father the devil.” Their spiritual lineage trumped their physical lineage. Whatever blessings they counted on as physical “sons of Abraham” were negated by their condition as spiritual “sons of the devil.” Entrance to the kingdom will not be based on physical DNA but on faith in the Son of God.
In Romans 9:6–7 Paul explains, “For not all who are descended from Israel are Israel. Nor because they are his descendants are they all Abraham’s children.” In other words, there are some people who are descendants of Israel (Jacob), but they are not part of the blessing of Israel. Likewise, there are some who are descended from Abraham but not “sons of Abraham” in a spiritual sense. Being a descendant of Abraham, Isaac, or Jacob is not enough. One must also now be a “descendant” of Christ. Of course, Christ had no physical descendants, but, at the end of Romans 9, Paul explains that those who have faith like Abraham had are made righteous before God, just as Abraham was. Those without faith in Christ, even if they are physical descendants of Abraham, are excluded; those with faith in Christ, even if they are Gentiles, are included as spiritual “sons of Abraham.”
In Galatians 3, Paul states it all plainly: “So also Abraham ‘believed God, and it was credited to him as righteousness.’ Understand, then, that those who have faith are children of Abraham. . . . So those who rely on faith are blessed along with Abraham, the man of faith” (Galatians 3:6–9). To be a “son” of someone is to have that person’s traits. To be the “Son of God” is to have God’s traits. To be a “son of Abraham” is to display a character quality of Abraham, namely, faith. Everyone who evinces faith is showing himself to be like Abraham in the sense that Abraham, too, had faith (Genesis 15:6).
Abraham heard from God and believed. Abraham’s faith caused him to leave everything behind and live the rest of his life as a stranger in a strange land. Abraham’s faith trusted that he and Sarah would have a child, even though that seemed impossible. Abraham’s faith was even willing to sacrifice the promised son, believing that God would raise him from the dead (Hebrews 11:9). Because of Abraham’s example of faith, the Bible points to him as the father of faith, as it were. All who similarly trust in the Lord are “sons of Abraham.” As Paul writes, “So in Christ Jesus you are all children of God through faith, for all of you who were baptized into Christ have clothed yourselves with Christ. There is neither Jew nor Gentile . . . for you are all one in Christ Jesus. If you belong to Christ, then you are Abraham’s seed, and heirs according to the promise” (Galatians 3:26–29).
God had promised Abraham that “all peoples on earth will be blessed through you” (Genesis 12:3). One way this prophecy is fulfilled is through the salvation that God grants to us, by grace through faith: “Know then that it is those of faith who are the sons of Abraham. And the Scripture, foreseeing that God would justify the Gentiles by faith, preached the gospel beforehand to Abraham, saying, ‘In you shall all the nations be blessed.’ So then, those who are of faith are blessed along with Abraham, the man of faith” (Galatians 3:7–9, ESV).
A children’s Sunday school song has the line “Father Abraham had many sons; many sons had Father Abraham.” It’s a truth of Scripture expressed simply in those lyrics and stated clearly in Galatians 3:29, “Now that you belong to Christ, you are the true children of Abraham. You are his heirs, and God’s promise to Abraham belongs to you” (NLT).