Romans 2:29
But the [true] Jew is the person who is one on the inside, and [his] circumcision is a heart condition, [produced] by the Holy Spirit and not by the written law of Moses. [Note: Some translate "Spirit" here as "spirit" and make it simply an amplification of "heart"]. This person receives his praise from God and not [merely] from people.
Romans 4:11
He received the sign of circumcision as a seal [confirming] that he had been [considered] righteous because of the faith he had before being circumcised. Thus, he became the [spiritual] father of all people who believe [in God], even though they have not been circumcised, so that they could be considered righteous [by their faith].
Colossians 2:11
In [fellowship with] Him you people were also circumcised with a circumcision not performed by human beings, but performed by Christ, consisting of the removal of the body of [sinful] flesh.