even to the Israel of God: The Greek word kai is usually translated as "and." It can also mean "even." If it means "and," then the Israel of God is a different group from all who walk by this rule. If it means "even," then they are the same group.
The Jewish people still have a special identity before God (Romans 9:1–5; 10:1–4; 11:1–32). Gentiles (non-Jewish people) who believe have been included, and Jews who do not believe have been removed from spiritual Israel (Romans 11:17–24; compare Philippians 3:2–3; Colossians 2:11–12). Paul sees all Christians as the true Israel (see Romans 2:28–29; 9:6–8; compare Galatians 4:21–31).
The phrase the Israel of God is not found elsewhere in the New Testament or other writings. Perhaps false teachers promised this identity to Gentiles who accepted circumcision. If so, Paul shows why their argument was wrong: The non-Jewish Christians in Galatia did not need circumcision, as they were already God's Israel—his true people—through faith in Christ.