A number of men in the Corinthian church were of Jewish background (see Acts 18:1–11). Consequently, they carried the mark of circumcision. In the Greek-Roman world, Jews were often mocked for this. Already by the second century before Christ, there were Jewish men who tried to reverse or hide their circumcision.
According to Paul, however, a circumcised believer has no reason to remove the marks of circumcision.
On the other hand, uncircumcised men should not seek circumcision
when they come to faith.
18 Was anyone at the time of his call already circumcised? Let him not seek to remove the marks of circumcision. Was anyone at the time of his call uncircumcised? Let him not seek circumcision.