Donald Trump’s latest outburst (for which, at least as of this writing, he has not apologized), in which he advocates not allowing Muslims into the United States until the US can “figure all this out”), is a new low for a buffoon who has continued to astound with the lows to which he can descend. One would have thought that mocking a person with physical handicaps, which he did a few weeks ago, would have constituted rock bottom.Alas, no.Jews, and particularly those who are – or once were – American Jews ought to be particularly revolted by the vulgar perversion of America that Trump now represents. Of course, Americans are frightened – they know that the likelihood is that San Bernardino was hardly the last – or the worst – of the attacks that are likely to hit the US in the months and years ahead.While there is cause for genuine fear, however, destroying what made America great in order to save America seems rather self-defeating. The American Jewish story is a story of extraordinary success precisely because the US to which our ancestors came was an America in which a religious test for immigration would have been anathema. The US has had horrendous immigration policies at times, including closing the borders to Jews during the Holocaust, but the fact remains that much of America’s greatness has been its (generally) religion- blind immigration policy.This week, Trump placed himself in direct opposition to what has long made America great.AND YET. At the opposite end of the spectrum from Trump’s mean-spirited ugliness is the self-destructive and self-deluding naiveté espoused by US President Barack Obama – and many religious leaders, including many rabbis, who want to pretend that we do not know what we know. There is something delusional and dangerous in continuously insisting that Islamic State (plus al-Qaida, Boko Haram – and others) do not represent Islam, that they are just “thugs” as Obama put it in his address to America earlier this week. That is both true and utterly false. Did Islam ever stand for something very different? Yes. Are there millions of decent Muslims who are appalled by what has happened to their religion? Undoubtedly.But if these are just “thugs” who do not represent Islam, why are there (according to conservative estimates) more than 50 million (and possibly close to 100 million) “radicalized” Muslims? Even “just” 50 million thugs is a lot of thugs. How many thugs does one religion have to spawn before the thugs are not a few cancer cells but a cancer that has metastasized and that has taken over the organism itself? When does the religion itself become a religion of thuggery? If the majority is opposed to the radicalization and the thuggery but says nothing, which group represents the religion? Are we going to see a Million Muslim Man March on Washington in which rank-and-file Americans will proclaim loud and clear that they are opposed to violence, to the idea of a Caliphate, to homophobia – and while they’re at it – to the demonization of Judaism and Israel? Are we going to witness a broad and public conversation in American Islam in which its leaders struggle with what role they played in allowing the hijacking? ON HANUKKA, those questions ought to occupy us as Jews, too. For what has always been wondrous about religion is the passion it evokes. But also what has always been dangerous about religion is the passion it evokes. Christianity, Islam, Hinduism and Judaism have all produced their malignant variants. No religious community can completely prevent the “radicalization” of a misguided few. But religions can be held accountable for what they do when they see the malignancy begin to take root. Islam waited far too long and may well have passed the tipping point.When Baruch Goldstein committed mass murder in the name of Judaism in Hebron, there was hardly a Jewish leader, from Reform to right-wing Orthodoxy, who did not insist that what Goldstein represented was simply not Judaism.But we have not eradicated the cancer.Still alive and well in Israel, for example, is Rabbi Yitzchak Ginsburgh, best known for his book Baruch Hagever, a double-entendre that can either mean “Blessed Is the Man” or “Baruch [Goldstein] Is the Man.” Ginsburgh’s screed is essentially a justification of Goldstein’s actions. Palestinians are Amalekites, Ginsburgh insists. And the Torah commands Jews to eradicate Amalek.Ginsburgh’s followers, Yitzhak Shapira and Yosef Elitzur, wrote Torat Hamelech (“Laws of the King”), suggesting that an argument can be made for killing innocent Palestinian children because they can grow up to become enemies of the Jewish people. How long was the road from Baruch Hagever to Torat Hamelech to Duma, where “radicalized” young Jews apparently burned a perfectly innocent Palestinian family to death? WHAT HAS Israel done to shut down this cancer? The Supreme Court refused to outlaw the publication of Torat Hamelech. But yeshivot can be taxed into collapse, can find their water and electricity cut off, watch their “rabbis” taken into administrative detention.Military exemptions can be revoked.All governments know how to use dozens of administrative mechanisms to make people’s lives miserable, to separate them from followers, to shut down their access to their followers. Israel has many tools at its disposal that it has not yet decided to use. Why? And at what potential cost? It is, of course, possible that going after Ginsburgh, Shapira and Elitzur would turn them into even greater heroes. But it’s worth remembering, especially on Hanukka, that the Maccabees were an insurgency, fighting for religious liberty against a seemingly much more powerful enemy. And for what they did to restore Jewish pride and independence (even if only temporarily), we celebrate them and their accomplishments.But insurgencies and their passions are often double-edged swords. What begins as a quest for freedom or pride can easily become derailed – and dangerous. Legitimately in the grips of fear at the horrors the West is now likely to see spread, we’re right to point out that the cancer that Muslims never eradicated has now taken over much more of Islam than American political correctness allows most people to acknowledge. Is it too late for Islam? Time will tell.But the mere fact that we have to ask that question ought to prompt us to ask ourselves what we are doing with those cells in our own midst.The Hasmoneans were, according to our liturgy, the weak against the mighty, the few against the many – and the pure against the defiled. Not all Jewish religious passion, however, is the “pure against the defiled.” Perhaps Hanukka is thus precisely the time to ask ourselves how we will ensure that our tradition will not be the next to be hijacked. ■ The writer is senior vice president, Koret Distinguished Fellow and chair of the Core Curriculum at Shalem College, Israel’s first liberal arts college, in Jerusalem. His latest book is Menachem Begin: The Battle for Israel’s Soul. He is now writing a concise history of the State of Israel.