1. Teach the Bible to yourself (17-24)

Paul reveals the sin of the Jews (or nominal Christians). They boast of superiority over non-believers for knowing God's Word and teaching the Bible. But knowing and teaching are different from living according to the law. So God's name is more blasphemed among the Gentiles because of nominal Sunday Christians' hypocritical and double life. The true Jew (true Christian) studies the Bible sincerely, seeks to obey the word repenting of double life, and teaches himself first before teaching others. They glorify God and save others.

2. Circumcise your heart (25-29)

Circumcision was an act of obedience to live as a covenant people. But it became a ritual. True circumcision is inward. It requires cutting one's heart to live as a covenant people as a life or death matter. It means to deny one's physical desires to live as the Word commands. The true Jew (Christian) not only goes to church (outwardly), but lives a life of following Jesus, circumcising the heart (repenting) and living by the Spirit.