Piper’s quick summary of God’s path, through Abraham and Israel, to save all the nations:
God chose Abraham and said “I will bless you to be a blessing, and through you all the nations of the earth shall be blessed” (Genesis 12, 15). Psalm 67 is a realization and praying into reality of that promise ahead of time. “May God be gracious to us and bless us…that your way may be known on earth, your saving power among all nations.”
God fulfills this through Christ, who is the seed of Abraham. All who belong to Christ — whether Jew or Gentile — become the seed of Abraham and are heirs according to promise.
Galatians 3:13: “Christ redeemed us from the curse of the law by becoming a curse for us so that in Christ Jesus the blessing of Abraham might come to the Gentiles” — that is, the nations. “Know then it is those who are of faith are the sons of Abraham.” “If you are Christ’s, then you are Abraham’s offspring — heirs according to the promise.”
“God’s plan to save the world is that he created it, it fell, and on his way to redeem the nations he chose a nation, Israel. You might say: ‘That’s strange. He focused on one nation for 2,000 years’. It is strange. That’s why Romans 11 is in the Bible. Romans 11 is all about why God took this strange, circuitous route to the nations through focusing first on Israel primarily for 2,000 years.”