Romans 9

"That is, it is not the children of the flesh who are children of God, but the children of the promise are regarded as descendants" (v8). Paul was deeply sorry that many of his "kinsmen according to the flesh" (v3) - fellow Jews - did not believe in Jesus the Messiah. Yet, he explained that God does not regard people as we do, in categories determined by blood and culture. Abraham had many children (Gen 25), but Isaac was the child of faith in God's promises.

From the beginning, God was forming "vessels of mercy" (v23) - a family of believers united by faith (10:13).