Who has the right to call himself a member of the Chosen People?
"Why, the Jews, of course", most people would reply. But Paul gives a different reply. Paul says that believers in Jesus Christ are the sons of Abraham. Believers in God's redeeming promise have always been the Chosen People.
In Romans chapter 9, Paul acknowledged that there was a physical aspect to being an Israelite; though outsiders were allowed to join the nation also, like Ruth. But Paul went on to distinguish between physical Israelites and "real" Israel. Descent from Abraham did not make anyone a child of God. It didn't always entitle you to Israel's earthly blessings! Ishmael was excluded from privilege even though he was Abraham's son. Esau was also excluded from the womb, even though he was Isaac's son.
God has always had a spiritual family that was never tied to any one ethnicity. Jesus taught this doctrine of spiritual family above blood kin. In one instance, Christ cried out, "Who is my mother, or my brother, or my sister? The one who obeys the word of the Lord is my mother, my brother, my sister!" (Mark 3:35). Christ also, when someone in the crowd cried out, "Blessed are the breasts that nursed you!", replied, "Blessed rather is he who hears the word of God and does it" (Luke 11;27).
So only those who believe are the sons of Abraham (Galatians 3:7). The children of Jews are not the real sons of Abraham. Neither are the infant children of Christians, since they do not believe. This is one reason why we should not baptize babies -- Paul says that the child of a Christian is not Abraham's child. Paul could not be clearer: Only those who are of faith are blessed with believing Abraham (Galatians 3:9).
The ceremony of circumcision stood for the entire Mosaic Law. It was the first law God gave (in Genesis 17) before He gave the Law (in Exodus 20). In the absence of that law God still accounted Abraham righteous, on the condition of Abraham's faith alone (Genesis 15:6). Abraham was an uncircumcised Gentile from the pagan land of Ur. He had no priest, no church, no water of baptism, no knife of circumcision. Yet God counted him righteous. This is why it was fitting that God said to Abraham, "Through you all the Gentiles shall be blessed" (Galatians 3:8).
This is why anyone who says that we must keep the Law to be saved has either sincerely mangled the Scripture, or they are motivated by pride (since Eophesians 2:8-9 says the reason God saves us apart from works is so that we cannot boast). Abraham made a decision of faith, in responding to God's promise, at a single point in time. At that exact time -- not later at the end of his life, but right then -- God saved Abraham.
A man or woman who is counted righteous by God does not need to keep the moral law in addition. That's like mailing mortgage payments to the bank, after a generous rich man has already paid off your loan. We would agree that anyone who kept trying to pay a debt that no longer exists is foolish. But to teach that we must keep the commandments to be saved, above-and-beyond Christ's payment for my sins, is even more foolish! Be wise!
God has no grandchildren. You become a son of Abraham, and enter into God's blessing of being accounted righteous in His eyes, by faith alone. Be glad! Instead of being shut out because of your ethnicity, the Lord welcomes you in no matter what nation your ancestors hail from!