But the [true] Jew is the person who is one on the inside, and [his] circumcision is a heart condition, [produced] by the Holy Spirit and not by the written law of Moses. [Note: Some translate "Spirit" here as "spirit" and make it simply an amplification of "heart"]. This person receives his praise from God and not [merely] from people.

And not only is this true, but we also rejoice in God, through our Lord Jesus Christ, through whom we have been restored to fellowship with God.

I am telling [you] the truth in Christ [i.e., since I am a Christian]; I am not lying. My conscience, [confirmed] by the Holy Spirit, supports my statements [as true],

This means that it is not the physical descendants [of Abraham] who are God's children, but it is the children [born] according to [God's] promise who are [Abraham's true] descendants.

For I can testify that they have an enthusiasm for God, but it is without [true] knowledge.

True, but they [i.e., the Jews] were [really] broken off because they did not believe [in Christ], and you [Gentiles] remain [in God's favor] because you do believe [in Him]. So, do not become arrogant [about it], but be fearful.