The covenant of circumcision is introduced in Genesis 17, and it later comes to occupy a central place in Paul’s Letters to the Galatians and Romans. For Paul, circumcision came to be seen as a form of religious identity within 1st century Jerusalem-based Judaism, with being circumcised taking precedence over following the Torah.
In Romans, he makes the point that, “For a person is not a Jew who is one outwardly, nor is true circumcision something external and physical. Rather, a person is a Jew who is one inwardly, and real circumcision is a matter of the heart—it is spiritual and not literal. Such a person receives praise not from others but from God” (Romans 2. 28 – 29).
It is this physical and external aspect of circumcision that is to us the most obvious characteristic, as the act is a physical one. So, how did Paul make the claim that real circumcision is a matter of the heart, being spiritual and not literal?
In Genesis 17, we hear the following:
This is my covenant, which you shall keep, between me and you and your offspring after you: Every male among you shall be circumcised. You shall circumcise the flesh of your foreskins, and it shall be a sign of the covenant between me and you (vv. 10 – 11).
Later in the same passage, we hear:
Abraham was ninety-nine years old when he was circumcised in the flesh of his foreskin. And his son Ishmael was thirteen years old when he was circumcised in the flesh of his foreskin (vv. 24 – 25).
The term “flesh of your/his foreskin” is repeated. If circumcision is what it is, the addition of “flesh” and “foreskin” seems unnecessary, so it naturally raises the question why it is included.
I believe the solution to how circumcision is actually meant to be a “spiritual circumcision of the heart,” is to be located in verse 14, which reads:
Any uncircumcised male who is not circumcised in the flesh of his foreskin shall be cut off from his people; he has broken my covenant (v. 14)
The “shall be cut off” is the biblical Hebrew word כָּרַת, which (according to Biblehub) may have the meaning of “to cut off; to cut down.”
In other words, Genesis likens circumcision to a branch of a tree being trimmed, in such a manner that Abraham is being challenged to, so to speak, “trim the branch he is sitting upon,” so as not be be cut off by God.
The physical act, then, is simply meant to actualize the trust. In this sense, Paul’s understanding of circumcision as an issue of trust/faith, and not of identity, is borne out by verse 14. Indeed, the issue of being “cut off” was foremost for Paul, which is why we hear him say in Galatians, “You who want to be justified by the law have cut yourselves off from Christ; you have fallen away from grace” (5.4).