If a Jewish man has children, they are only considered Jewish if the mother of those children was Jewish. So yeah, Jewish boys are supposed to marry Jewish girls if they want to continue the whole Jewish thing. The boys are Jewish because they had a Jewish mother, but if they don’t marry a Jewish woman themselves then their children will not be Jewish.
My mom was raised a Hasidic Jew in Poland before the war. My mothers father was a rebbe for the community. Both my parents are (were, my dad recently died) survivors. Much of my family is in Israel, as my parents were when my dad fought in 1948.
I’ve never in my whole life seen either my parents view any denomination as being more or less righteous, or close or far from Judaism.
AHHHHHH! That’s the real question, isn’t it?
Back to my hypothetical character, Ken Greenberg. His father is Jewish, his mother is Italian. He’s was baptized Catholic, but rarely went to church, and is currently an agnostic leaning toward atheism.
If he wanted to marry an Orthodox Jewish woman in an Orthodox synagogue, the rabbi there would undoubtedly say “Ken is NOT a Jew,” and I wouldn’t argue with him.
And if Ken wanted to move to Tel Aviv and become an Israeli citizen, the Israeli immigration officials would undoubtedly say “Ken is NOT a Jew.” Again, I wouldn’t argue with them.
On the other hand, if Ken is a friend/acquaintance of mine, and he tells me “I’m Jewish,” I’m not inclined to argue with HIM either. There are religious and national standards for who’s a Jew, and as a Goy, I accept that I’m not entitled to an opinion on those matters.
But on a personal level, if Ken Greenberg (or Max Baer or Gwyneth Paltrow or Lenny Kravitz or Paul Newman) told me, “I’m Jewish,” I’d accept that without hesitation, even if no rabbi would.
The Israeli immigration official might say that Ken is not a Jew, but he’d still grant him Israeli citizenship. Non-Jews with a Jewish parent or grandparent are entitled, on the basis that they’re Jewish enough to be killed for it.
The question of whether someone is/isn’t Jewish depends partly on the point of view and the reason for the question.
For Hitler and the Nazis, having one Jewish grandparent made you Jewish, and many were murdered even though they (and their parents) had been raised as Christian.
For the state of Israel’s legal perspective (admission to citizenship), being Jewish means having a Jewish mother (being born Jewish) or being converted by a recognized rabbinic authority. (The meaning of “recognized” is a very nasty political squabble.)
For the perspective of Reform Judaism, I beg to differ (strongly) with the prior posts: it is NOT simply a case of having one Jewish parent. It’s having one Jewish parent AND being raised Jewishly. (Lots of people forget that AND when discussing this topic, but it was a critical part of the Reform decision.) Or, of course, by conversion by any rabbi.
For most Orthodox, being Jewish means being born of a Jewish mother or having been converted by an Orthodox rabbi. For Conservative, ditto ditto except conversion can be by either an Orthodox or Conservative rabbi.
If you’re in a synagogue and asked whether to have an aliyah (an honorific position during torah reading), you are supposed to be Jewish. They won’t ask for proof, you’d be accepted as Jewish if you said you were.
It is also possible (at least philosophically) for someone to “be Jewish” in the sense of practicing Judaism, without “being Jewish” in the sense of belonging to the ethnicity/people.