In Galatians 3 Paul gives a concise overview on how the Jews, Gentiles, and covenants interact in the gospel of Jesus Christ. The final paragraph of Galatians 3 reveals a wealth of information and clarification on the gospel.
(Galatians 3:23-29 ESV) Now before faith came, we were held captive under the law, imprisoned until the coming faith would be revealed.  So then, the law was our guardian until Christ came, in order that we might be justified by faith.  But now that faith has come, we are no longer under a guardian,  for in Christ Jesus you are all sons of God, through faith.  For as many of you as were baptized into Christ have put on Christ.  There is neither Jew nor Greek, there is neither slave nor free, there is no male and female, for you are all one in Christ Jesus.  And if you are Christ's, then you are Abraham's offspring, heirs according to promise.
Part 3: Verse 26 – Sons of God.In verses 23-25 Paul was speaking of Jews who were under law as evidenced by his use of the pro-nouns we and our. But here in verse 26 Paul changes to the pro-noun you. With the coming of the New Covenant, salvation now included the Galatian Gentiles and Gentiles everywhere that were in Christ through faith. Therefore, both Jews and Gentiles are sons of God through faith. Paul explains thoroughly in Romans 9 that it is not the physical children of Abraham that are the sons of God, but it is the children of the promise. Thus, flesh counts for nothing in spiritual salvation, but only faith. Faith alone makes a person a child of God and being a Jew or the offspring of a New Covenant believer does not put a person in a New Covenant relationship with God.