I appreciate and agree with Iain Duguid’s discussion of “replacement theology” in his commentary on Numbers 24:
Some Christians believe that Old Testament promises that speak of “Israel” are only intended for ethnic Israel and not for the church. For them, Balaam’s prophecies speak of a glorious future for the physical descendants of Israel, but they would call any attempt to apply these promises to the church “replacement theology.” I would suggest that this is a misunderstanding of what the Scriptures teach about Israel. It is not that the church has replaced Israel in the New Testament so much as that Old Testament Israel—ethnic Israel—finds its true goal and fulfillment in the person of Jesus Christ. Jesus is himself the star of Jacob, the Israel of God.
In the person of Jesus, therefore, the true Israel has arrived, and all those who come to God by faith in him—Jews and Gentiles alike—become God’s children and are thereby incorporated into this new people of God (John 1:11, 12). In Christ, Jews and Gentiles together become the true heirs of the promise given to Abraham, his spiritual descendants (Galatians 3:29). Outside of Christ, on the other hand, there is no longer any true Israel. It is those who are in Christ who are the true chosen people: a royal priesthood, a holy nation, a people belonging to God (1 Peter 2:9). We have been chosen by God for exactly the same special relationship that he had with his Old Testament people. In his incredible grace and mercy, God chose us before the foundation of the world, so that we might be blessed in Christ with every spiritual blessing (Ephesians 1:3, 4). He has rescued us from the final judgment that awaits all those who remain outside his people and has given us the glorious inheritance of a relationship with himself. In Jesus, the star of Jacob has risen for us and for our salvation.
Covenant Presbyterian Church (OPC)