One of my favorite concepts in logic is the reductio ad absurdum (Latin: “reduction to the absurd”) argument, which is a logical method of argument that proves the falsity of a premise by following its implications to a logical but absurd conclusion.
“Fortifying the Walls of Conversion” ?
Today, at a conference dedicated to “fortifying walls of conversion,” the Israeli Chief Rabbi Yona Metzger expressed moral support for Rabbi Sherman, who annulled thousands of conversions carried out by Rabbi Chaim Druckman, who has been the past acting director of the National Conversion Authority in Israel.
In the past couple of years or more, Haredi politicians in Israel have on a number of occasions tried to oust the rabbi, most notably under the corrupt leadership of Prime Minister Ehud Olmert , but Rav Druckman refused to go and there was nothing his critics could do to force him to leave. Even after his departure from the directorship, Haredi politicians and rabbis are still trying to overturn all of his conversions, which may affect the status of about 15,000 converts in Israel.
Explaining Why Revoking Conversions is Wrongheaded
The concept of revoking a conversion is a recent innovation in rabbinic law. As we have posted in other places, the Shulchan Aruch (Code of Jewish Law) does not sanction revocation of conversions at all. Should a convert return to his former gentile roots, the halacha still considers him as a “sinful Israelite.” 
Simply stated, revoking conversions is risky business and can cause unspeakable harm to countless innocents who are indirectly or directly triangulated in the rabbinic web the Haredi rabbis have woven.
Reductio ad absurdum in Action
Say, for example, a woman converts from Catholicism and becomes a pious Haredi Jewess at the tender age of 20; she then raises a Haredi family and has 20 children of her own–all who live pious Haredi lives. Now each of those 20 children of the second generation have 20 children of their own, and they too, remain pious and God fearing Haredim.
As time passes, each person of the the third generation of 20 children produces 20 children–all who remain within the Haredi community.
Perhaps the original matriarch lives to see a fourth generation of Haredi children, who in turn have 20 Haredi children. Thus we have four generations of Haredi children–all related to their Haredi great, great, great grandmother.
If we look at the sheer numbers, we thus have 20x20x20x20 = 160,000 people–not bad for this one prolific Haredi family!
At this point, ask yourself a simple question:
What would happen to the status of all those generations of Haredi Jews, if the original convert decides to return to her original Catholic faith on her 120th birthday?
That decision, according to Haredi logic, would jeopardize the Jewish status possibly of up to four generations of Haredi Jews, equaling more than 160,000 Jews! Our reductio ad absurdum argument explains why our ancestors had the common sense not to revoke conversions. Rather, they considered the wayward convert as a “cho’te Yisrael” ( a “Jewish sinner”).
Children must not be penalized for the sins of the parent, our tradition teaches us. Creating artificial halachic barriers will not solve the problem, it will only compound it–even lead to an exponentiation that will create scandal for everyone.
While I believe the Haredi community has every right to define who they wish to recognize as a bona fide member of their community. However, their Haredi rabbinic leaders do not have the right to legislate for communities outside of its jurisdiction. That has always been the case in the history of Jewish law. Every community is autonomously responsible for its members.
Still and all, within a decade, the Haredi may prove to be an unstoppable political force in Israel; this is definitely bad news for the rest of us Jews!
 What exactly does Jewish law say about a convert who abandons his observance of Jewish law? Consider the Shulchan Aruch YD 268:12 that reads:
סעיף יב שולחן ערוך יורה דעה הלכות גרים סימן רסח
כג כו] כשיבא הגר להתגייר, בודקים אחריו שמא בגלל ממון שיטול או בשביל שררה שיזכה לה או מפני הפחד בא ליכנס לדת. כז] ואם איש הוא, בודקין אחריו שמא עיניו נתן באשה יהודית. ואם אשה היא, בודקין אחריה שמא עיניה נתנה בבחורי ישראל, ואם לא נמצאת להם עילה מודיעים להם כובד עול התורה וטורח שיש בעשייתה על עמי הארצות, כדי שיפרשו. אם קיבלו ולא פירשו, וראו אותם שחזרו מאהבה, מקבלים אותם. ואם לא בדקו אחריו, (ט) או שלא הודיעוהו שכר המצות ועונשן, ומל וטבל בפני ג’ הדיוטות, ה”ז גר אפי’ נודע שבשביל דבר הוא מתגייר, הואיל ומל וטבל יצא מכלל העובדי כוכבים, וחוששים לו עד שתתברר צדקתו; כח] ואפילו <טז> חזר ועבד עבודת כוכבים, הרי הוא כט] כישראל מומר שקדושיו קדושין. כד (ישראל מומר שעשה תשובה, א”צ לטבול; ל] רק מדרבנן (י) יש לו לטבול לא] ולקבל עליו דברי חבירות בפני ג’) (נ”י פ’ החולץ).