God's people are not the same as Paul's people. Some are; but not all. Paul's people, his lineage, as he says, are those of the physical circumcision, the Jews.
God's people, all believing Jews and Gentiles, are those whose hearts have been circumcised.
"For circumcision verily profiteth, if thou keep the law: but if thou be a breaker of the law, thy circumcision is made uncircumcision." -- Romans 2:25
And which Jew or which Gentile can keep the law perfectly?
NONE.
So the physical circumcision means nothing and profits nothing.
But he is a Jew, which is one inwardly; and circumcision is that of the heart, in the spirit, and not in the letter; whose praise is not of men, but of God." -- Romans 2:28-29 "For he is not a Jew, which is one outwardly; neither is that circumcision, which is outward in the flesh:
No Gentile was ever under the Law -- only Jews.