So everyone who obeys the Law, but has never been circumcised, will condemn you. Even though you are circumcised and have the Law, you still don't obey its teachings.
Later, God removed Saul and let David rule in his place. God said about him, "David the son of Jesse is the kind of person who pleases me most! He does everything I want him to do."
To be a real Jew you must obey the Law. True circumcision is something that happens deep in your heart, not something done to your body. And besides, you should want praise from God and not from humans.
He makes us worthy to be the servants of his new agreement that comes from the Holy Spirit and not from a written Law. After all, the Law brings death, but the Spirit brings life.