Merriam-Webster's definition: "a person who is not Jewish"
The law of the State of Israel:
The Law of Return
July 5, 1950
Amendment No. 2 5730-1970*
1. In the Law of Return, 5710-1950**, the following sections shall be inserted after section 4:
4B. For the purposes of this Law, "Jew" means a person who was born of a Jewish mother or has become converted to Judaism and who is not a member of another religion.
This is how the State of Israel defines Jew.
Yeah, I know, I have Jewish friends in Israel and friends who have had to prove their Jewishness by todays standards.
But Scriptural context and definition says otherwise.
You're trying to cram today's definitions back 2000 years.
Paul's context is Israel vs the nations/gentiles.