Galatians 6:15

For he is not a Jew who is one outwardly, nor is circumcision that which is outward in the flesh.

Therefore we were buried with Him through baptism into death, so that as Christ was raised from the dead through the glory of the Father, so we too might walk in newness of life.

Circumcision is nothing, and uncircumcision is nothing, but what matters is the keeping of the commandments of God.

Therefore if anyone is in Christ, he is a new creation; the old things passed away; behold, new things have come.

For in Christ Jesus neither circumcision nor uncircumcision means anything, but faith working through love.

For we are the circumcision, who worship in the Spirit of God and boast in Christ Jesus and put no confidence in the flesh,

The one who believes in the Son of God has this witness in himself. The one who does not believe God has made Him a liar, because he has not believed in the witness which God has borne witness about His Son.