One of the big issues threatening to blow up the world* is that of conversions. In Israel right now, there appears to be a big hullaballoo over whether the conversions performed by the IDF rabbis were valid. Traditionally, conversions into Judaism involve the convert at some point accepting to keep all of the mitzvot in the Torah. At some point in the last few hundred years this became mandatory practice (it appears this definitely was not always the case), and it looks like the IDF rabbis were/are not sticklers on that last part. This is a big deal, because the conversions in question are largely conversions of the Russian immigrants that were oleh in the last 20 years, after the collapse of the Soviet Union. There are estimated to be about a million of them, practically all of whom consider themselves Jewish, but a theoretically substantial minority of which don't have a technically Jewish mother, meaning they technically require conversions.
From what I can tell, there appear to be two camps. On one extreme, you have the chareidim, led by Rav Elyashiv, who believe that since "everyone knows" these converts had no intention to actually keep all the mitzvot, their conversions are invalid, and indeed, never were valid. Sephardim, led by Rav Yosef, argue that the conversions are fine. I don't really care about the finer technical points of the dispute, and while I apologize if I've mischarachterized anything, it's not really germane to my point.
My question is, what really makes a Jew a Jew? I don't think Rav Elyashiv thinks that our conversion standards have always been the same, and that we have always required the honest acceptance of the mitzvot, because the rishonim certainly don't reflect such uniformity. Rather, it seems to me, the title or status of Jew is something the community bestows upon a person. In the old days, if someone acted like a Jew, and thought of himself as a Jew, others would too, and that was enough. By the same token, that seems to be the way it works today. Nobody checks my lineage. Rather, I go to shul, I keep shabbos, and I eat kosher, so I'm Jewish.
I don't think there's some objective record of who's really really Jewish up in Heaven that G-d has, and to get on that list, you have meet a very concrete and specific line of regulations. If we think you're Jewish, you're Jewish. Definitely, no one has completely pure yichus without one single gentile in their family, or can vouch 100% that they know that any potential converts on their mother's side in the last 3000 years were mekabel chiyuv mitzvis. Certainly these "lost Tribes" we keep finding in Africa or India or China can't do that, and it's funny that we all just "pretend" they're "really" Jewish.
I think the only reason we have any objective standards at all is just so that the status of Jew doesn't become meaningless. If it was just a listserve or something that you sign onto, what good is it? That's fine, and I think that makes sense. That explains why Judaism requires that you marry Jewish - it's more likely that your children will be raised Jewish if both spouses are committed to their Jewish heritage. But in this situation, I think we've got that. These are immigrants who have come to the Jewish state to embrace their Jewish and Israeli heritage. They serve in the Israeli army, build illegal settlement outposts, and run on racist Jewish-supremacist party platforms to become the foreign ministers of the Jewish state. To me, there is no greater acceptance of Jewish heritage than those things. We don't have to worry that they secretly are celebrating Christmas or going to church or planning pogroms in their basements. It's not as if marrying them will really dilute Judaism in any effective way. Also, there are like a million of them living in a country with a tenuous Jewish majority, and writing them out of Judaism right now would be a really stupid idea.
Jews are who we say they are. If all the Rabbis got together and said, these people are Jews, everyone would be fine with that. Everyone would accept that. So I would really wish Rav Elyashiv would take a pragmatic approach here and recognize that he has agency. These guys are just as Jewish as any non-frum Jews. As long as Rav Elyashiv says so.
*The world of Torah, that is!**
** I.e., the only world that counts, mister.