You are confusing Judaism - the religion, with the Jewish people - an ethnorelegious group. Many modern Jews are atheists - they certainly don't believe in Judaism, yet nobody would doubt that they are Jewish, nor would they deny this themselves. Similarly - a Jew can become a christian or a muslim yet ethnically still remain a Jew. The same cannot be said about christians or muslims.
>a Jew can become a christian or a muslim yet ethnically still remain a Jew
I completely agree with your comment, and not only that but also find your view on the quote interesting as well.
A lot of Jews would say that any Jew who becomes a Christian is no longer Jewish (by ethnicity or religion) even if said "Jewish Christian" still abides by and observes many Jewish customs and holidays.
A lot of Jews are still mad that the greatest man among them started the most successful and enduring sect of Judaism ever, and then had the gall to welcome foreigners.
I may still be confused, because without the term Jewish people, it would seem that many adherents to the Jewish faith which are not ethnically Jewish would not be considered Jews?
I would argue that there are also many atheist Catholics (e.g. in Italy) who would disagree that they were not also part of an ethnorelegious group.
