Circumcision of the Heart in the New Testament:
Acts 7:51
"Ye stiffnecked and uncircumcised in heart and ears, ye do always resist the Holy Ghost: as your fathers did, so do ye."
Spiritual Circumcision in the New Testament:
Philippians 3:3
"For we are the circumcision, which worship God in the spirit, and rejoice in Christ Jesus, and have no confidence in the flesh."
Romans 2:28-29
28 "For he is not a Jew, which is one outwardly; neither is that circumcision, which is outward in the flesh:
29 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."
Colossians 2:11
"In whom also ye are circumcised with the circumcision made without hands, in putting off the body of the sins of the flesh by the circumcision of Christ"