The prophet Yishayahu (Isaiah) famously prophesised that the destroyers and ruiners of Israel will come from within it. The decision of the Beth Din HaGadol (the high rabbinical court in Jerusalem) to annul the conversion to Judaism (giyur) of thousands of people seems to be an example of this prophecy coming true in our times.
A short background. In the early 1990s, more than one million Jews from ex-USSR immigrated to Israel. By many measures, this aliyah was one of the greatest things that happend to this country. The absorption of most of these olim into Israeli society is one of the underrated successes of Israel's young history as a nation-state. However, not all is positive. For reasons I will not go into here, many of of these immigrants (some say a third, perhaps even more) are not Jews according to Jewish law (halachah). A commendable initiative by the government set up tackle this issue by founding a special conversion administration to convert those who wished to integrate fully into Jewish society. This special beth din, headed by rabbi Haim Drukman, has converted thousands of people to date, many of them young men and women during their military service.
Israel has enough social problems and it cannot afford to keep a sizable part of its population in limbo, as "quasi-Jews". As has happened several times in Jewish history, Israel embraced a lenient approach to conversion in order to accept these Israelis as full Jews, while at the same time keeping the requirements of halachah in the process. This was the right solution at the right time.
Now comes the high rabbinical court and, while ratifying a decree by a district rabbinical court in Ashdod last year, concludes that ALL conversions done by rabbi Drukman's beth din since 1999 are void. No less. Tousands of families in Israel who underwent the arduous process of giyur willingly, are suddenly "not Jewish" according to these rabbinical judges.
As was correctly pointed out by other rabbis (example) the halachah explicitly states that, regardless of what a person does after he has completed his conversion, "once a Jew always a Jew". A conversion cannot be reversed, even if the person suddenly starts worshipping Buddha, let alone if he merely does not follow mitzvot as stringently as the rabbis would like him to. The Jerusalem rabbis may dislike the government's initiative and rabbi Drukman's work (for reasons we shall conveniently ignore for now), but they cannot nullify a giyur once it has been completed by an authorised orthodox beth din.
Even if we ignore the direct halachic ramifications of their act, these rabbis are committing what is in my view a terrible mistake. They take people who have joined our country (never mind for what reason) and then chose to remain here as law-abiding citizens, integrating into Israeli-Jewish society and accepting full responsibilities - including serving in the military, which these very same rabbis refuse to do! - and purport to tear them apart from the "real Jews". This is unforgivable and I can only attribute it to the short-sighted, cowardly approach of ultra-orthodox Judaism in recent decades.
I hope that the religious and non-religious outcry against this decree will reverse the situation quickly, or else the words of the prophet will come true.