The Forgotten Rule of Paul
When asked, almost no one in the Christian world can answer this simple question: What unique rule did the Apostle Paul set in all his congregations?
In response to a letter sent by the leaders of the Corinthian congregation, Apostle Paul wrote: “... each one should retain the place in life that the Lord assigned to him and to which God has called him. This is the rule I lay down in all the congregations. Was a man already circumcised when he was called? He should not become uncircumcised. Was a man uncircumcised when he was called? He should not be circumcised.” (1 Corinthians 7:17-18)
The ancient world had no concept of conversion from one religion to another. This was largely because religion did not exist as a separate category from "peoplehood" (i.e. belonging to a people). When people “converted,” they did not convert from one religion to another, but from one people group to another. Individuals, from both Israel and the Nations, were sometimes willing to fully cut ties with their communities and switch communal alliances. Some Jews actually went through surgery that removed the signs of circumcision; while some non-Jews fully (not partially) adopted Jewish ancestral ways of life (the code word for which was "circumcision").
The great apostle believed that both Israel and the Nations, while retaining their distinct identities, must offer joined worship to Israel's God. In the New Covenant community of Israel, discrimination and preference between Jews and the Nations was now strictly forbidden; while the functional distinction between them was rightfully upheld. For example, even though men and women were ONE in Christ, women were still (in a very important sense) women and men were still men (Gal.3:28).
Paul’s reasoning was simple: If Gentile Christ-followers became Jews, then the God they worship would be too small. He would be the God of the Jews only. However, if Gentile Christ-followers, as the Nations, would worship Israel’s God alongside the Jews, then the grandeur of this One God would become evident to all (Romans 3:28-30).