Galatians 3:29

Verse 29. And if ye be Christ's. If you belong to the Messiah, and are interested in his work. Then are ye Abraham's seed. The promise made to Abraham related to the Messiah. It was a promise that in him all should be blessed. Abraham believed in that Messiah, and was distinguished for his faith in him who was to come. If they believed in Christ, therefore, they showed that they were the spiritual descendants of Abraham. No matter whether they were Jews or Gentiles--whether they had been circumcised or not--they had the same spirit which he evinced, and were interested in the promises made to him. And heirs according to the promise. See Ro 8:17. Are heirs of God.