'Circumcision' in the Bible

In Him you were also circumcised with a circumcision not made with hands, but by the [spiritual] circumcision of Christ in the stripping off of the body of the flesh [the sinful carnal nature],

and from Jesus, who is called Justus. These are the only fellow workers for the kingdom of God who are from the circumcision (Jewish Christians), and they have proved to be an encouragement and a comfort to me.