Religious people, is it impossible to be a white Muslim or a black Jew?

There are plenty of both.

No, neither is impossible.

You can be a white Muslim or a black Jew. But not Jewish ethnically. And Muslim isn’t a nation or ethnicity.

Since there are both white Muslims and black Jews, no.

Cat Stevens/Yusuf Islam is a white Muslim

Sammy Davis Jr and Nell Carter were black Jews

 nope not at all

Of course it's not.  There are white Muslims - you probably can't see them under their veils and under the Covid masks!!!!!!! 

 There are also black Jews of course, but nobody goes about advertising openly that they are circumcised, do they?  So how would you know one way or the other whether a black man you encountered in the street was a Jew or a Gentile?  You would have to ask.

Go to a Synagogue.

Just out of interest.  Why do you want to know anyway?

Yes, Sammy Davis, Jr was a black Jew. White people can and do convert or are born Muslim. 

look up  sephardi Jews  and mizrahi  jews   of Africa    read the bible    Moses  wife zipporah

and solomon's wife   makeda queen of sheba  both women of color

DIFFICULT  does NOT EQUAL   UNTRUE ...... DIFFICULT  word use  needing much effort 

There are both white Muslims and black Jews.

People sometimes convert from one religion to another or, if they never believed anything at all where a god is concerned, they might suddenly start believing that there must be a 'god' of some kind. If they begin studying the subject some might begin to believe that Christ is the Messiah whilst others might come to the conclusion that they should be following the teachings of some other 'god' or prophet.