Why does Israel never attain to the position of being called children of God that the Body of Christ enjoys?
Because this position of being called children of God belongs to members of the Body of Christ through their salvation experience, a relationship Israel has never enjoyed and never will attain. Gentiles once outside Israel's God are now called out and called children of the living God, while Israel remains God's covenant people.
Les teaches that "children of God" is a term Israel has never enjoyed and never will; members of the Body of Christ enjoy a position even Israel will never attain. He identifies the Church as the Bride of Christ, joined heirs with Christ, who will rule and reign with Him, and describes this relationship as being the very born ones of God by virtue of the salvation experience. Turning to Romans 9:25–26, he applies the calling of those who were "not My people" to Gentiles, who were never reckoned in the Old Testament as having anything to do with Israel's God, but are now called out and called the children of the living God. After God is through calling out this people, He will turn back to His covenant people, Israel.