1 Corinthians 7:18 Is any man called being circumcised? let him not become uncircumcised. Is any called in uncircumcision? let him not be circumcised. 19 Circumcision is nothing, and uncircumcision is nothing, but the keeping of the commandments of God.20 Let every man abide in the same calling wherein he was called.
Here Paul is clarifying an issue that the Jewish Christians felt the gentiles should abide by and Paul was saying not. Paul needed to clarify the issue by saying that neither was necessary, the idea is that when a Jew became a Christian that he was not to give up his racial and cultural identity in order to appear like a Gentile. The same for a Gentile they were not to become culturally like a Jew. Culture and social order and external ceremony have no bearing on spiritual life because what matters is faith and obedience. Verse 19 continues to say that it does not matter if you are circumcised and become a Christian it is ok and if you are not circumcised and become a Christian it is ok. We are to accept people the way the Lord does because circumcision was a law Jesus fulfilled on the cross. Lastly he states here that if the Lord approved of your calling who is man to question what the has ordained.