Last August, attending a family bat-mitzvah in Jerusalem, I met and had a long talk with a young man. He was, I learned as we spoke, part of the so-called “Price Tag” group, that shot to world attention last month with a wedding video from hell: young skullcap-wearing Israelis dancing feverishly, singing songs of revenge, brandishing knives, guns, a Molotov cocktail and a photo of Ali Dawabsheh, a toddler killed by Jewish extremists who firebombed his family’s home this summer, with a dagger stuck through the photo. Two have since been indicted for the murder.

Watching this, many people have asked themselves, can these hooligans be Jews, religious Jews? The answer is yes. But where do they come from, and who are they? The answers to those questions raise others, which hit me once again after that conversation in Jerusalem: How can moderates and liberals talk convincingly to people turning to radicalism around the world?

The wedding dancers have been condemned across the Israeli political spectrum, including the Religious Zionist and settler groupings from which they have arisen. Religious Zionism, decades ago, not only made peace with but actively embraced the secular democratic Israeli state; in recent years, it’s come to see itself as the new elite and successor to secular Zionism, which to its mind is adrift and incapable of solving Israel’s problems. Religious Zionism now supplies fully one-third of the IDF’s combat units and is increasingly prominent in politics, hi-tech, and, interestingly, arts and culture. Its ideological criticisms of secularism notwithstanding, it is sincerely committed to the State and the civic Jewishness of Zionism.

At the same time, taken together, the assertiveness of Religious Zionist activism in the territories and the moral corrosions of occupying another people, the collapse of the Zionist left and, yes, Palestinian rejectionism and violence, have led to the emergence of new and frightening ideologies.

Israel’s ‘alien values of Western democracy’

The last decade and a half has seen the emergence in the biblical heartland of the West Bank of a radical offshoot of Religious Zionism, known as “the hilltop youth.” Young people, many having grown up in settlements, rejecting what they see as the religiously compromised, bourgeois lifestyles of their parents, and of the State of Israel as a whole. Organic farming, soulful prayer and music are very much a part of their Bohemian lives. And for some, so is fighting with Palestinian Arabs and with the Israeli security services, with whom they are on both intimate and inimical terms. (The IDF does not draft or induct those hard-liners into its ranks.)

Religiously, they are a mix of Orthodoxy and anarchy, living lives structured by traditional Jewish law, but interpreting it on their own with scarce deference to Rabbinic authority. And, like young people everywhere, they are active on social media and the web.

The extremist wing, small but headline-grabbing, engages in so-called “Price Tag” attacks, usually in retaliation for Israeli government moves to restrict settlement activity in one form or another. The proximate victims of these attacks are Arabs, mosques, churches – but, as the young man at the bat-mitzvah said to me this summer, confirming the views of other analysts, the real target is the sovereign State of Israel.

Israel itself, he explained, is a mongrel hybrid of watered-down Judaism and alien values of Western democracy. Then, speaking like a classic Leninist revolutionary, he said that violence, properly applied, will enflame the region, force both the contradictions of Zionism and the inevitable Jewish-Arab Armageddon to the surface, leading to the toppling of Israel — to be replaced by the longed-for Jewish kingdom, high rabbinic court and temple. I asked him what made him different from the ultra-Orthodox who also reject in principle Israel’s synthesis of Jewishness and Western democracy. “They,” he said, “don’t want to antagonize the Goyim. I do.”

In a subsequent exchange I asked him how he differed from ISIS. “The central difference,” he said, “is that Judaism is uninterested in ruling the world and forcing everyone to be Jews,” just that they abide by basic universal, moral principles. That being said, he went on, there should be no churches or mosques in the Holy Land, and ideally all Jews in the restored kingdom should be made to observe traditional Jewish law, certainly in public, whether they want to or not. (Interestingly, he noted that he would count himself among the to-be-coerced when it came to the place of women in religious life and society, where he is more liberal-minded than his friends.)

How can a moderate talk to a fanatic?

Talking to him I’ve seen just how unconvincing my familiar liberal pieties were, for several reasons. First, ever since the Second Intifada began in 2000, the Israeli left, though it sees Israel’s long-term political dilemmas clearly, has had an increasingly hard time giving good answers to the well-grounded fears of ordinary people. Palestinian rejectionism has fueled Israeli hard-liners and helped bring out the worst in Israeli politics. The recent wave of knife-wielding terror attacks has only driven up already well-grounded fears.

Moreover, young people on both sides who have known violent conflict all their lives, see hatred all around them, and have had little experience of living peaceably with people unlike them, have a hard time believing in sweet reason and moderation, as they have seen little evidence of its suasion in their own lives. Racism and xenophobia are at work on both sides, officially in the Palestinian Authority’s education system, and unfortunately it seems to be taking root in Israel too.

Second, people driven by deep religious conviction will not be moved by arguments that do not reckon with their own commitments, or are too anemic to offer a serious alternative to their way of seeing. Liberal religion not grounded in metaphysics, and in compelling readings of religious texts and traditions that answer the potentially violent teachings to be found in all religions, as in all ideologies – is unconvincing and useless in the face of evil.

You don’t have to be religious to be morally strong. Secular Zionism in its heyday laid solid claim to Jewishness due in no small part to powerful moral messages of rescue and social justice, and the willingness of its adherents to sacrifice and even lay down their lives. The more secular Zionism has abandoned the language of Jewish ethics and adopted the vocabulary of generalized globalized human rights, the less familiar and convincing it has become to many Israelis, and especially to the young people we’re talking about. In other words, it is precisely the weakening of the classic Zionist ethos that has led to the cultural malaise that religious fanatics and worse are glad to fill.

And not only in Israel. Western democracies desperately need to recapture basic values of citizenship, of shared participation in pursuit of the common good, if they want to survive onslaughts from without, demoralization from within and maintain robust freedom.

Condemning the wedding dancers is necessary, but also easy. We have to fight to the end the deadly fanaticisms that threaten to destroy our world. At the same time, we need to forge a language that speaks to people driven to fanaticism. Religion, for good and for bad, isn’t disappearing anytime soon, nor are passions of any kind. Liberals and moderates everywhere need to talk not just about values, but about meaning. We don’t need to forge common language of agreement with radicals and the right. But we do need to forge a common language of argument, at the most basic levels of human existence.

Only a common language, and much conversation, will reveal how all sides see their interests, values and experience of the world. This can’t make all violence go away, and may sound Utopian. But if we don’t offer common language with people with whom they deeply disagree as an ideal, we condemn ourselves to an even longer and bloodier war.

Yehudah Mirsky, an American-Israeli and former State Department official, teaches at Brandeis University, and is author of “Rav Kook: Mystic in a Time of Revolution” (Yale University Press). He tweets @YehudahMirsky