‘If the rebels win the vote today, we’ll have been Feiglinized,” declared Omri Sharon, the prime minister’s son and political right-hand man, over the weekend. The “vote” was Sunday’s election in the 2,500-member Central Committee of the Likud. Up for grabs were three key positions that control the party’s internal apparatus.

For each of these positions, there was a pro-Sharon candidate and a “rebel” or anti- Sharon candidate who opposes the prime minister’s Gaza disengagement plan. In essence the vote was over this plan, and the prime minister’s supporters won by a narrow margin in all three cases – a reversal of the results of the Likud referendum on disengagement held last May, in which 60% of registered party members participating voted “no.” But who is Mr. Feiglin? His name wasn’t one of the candidates’. Few outside of Israel have heard of him. What was Omri Sharon saying?

Moshe Feiglin is a religious West Bank settler of extreme nationalist views who first came to the attention of Israelis following the signing of the Oslo agreement in 1993, when he organized and led an extra-parliamentary protest group, called Zo Artsenu, “This Is Our Country.” The protesters staged anti-Oslo demonstrations of a sometimes massively disruptive nature, such as tying up traffic simultaneously on all of Israel’s main roads by staging sit-ins at major intersections, and Mr. Feiglin was later convicted by Israel’s courts of incitement to riot and sentenced to prison in 1997.

Released after three months, he decided to turn to more conventional channels. For a while he founded and headed a right-wing lobby called “Jewish Leadership.” Then, persuaded that this, too, was not the way to affect Israeli politics, he came up with a new idea.

This idea was simple and ingenious. Heretofore, the more militant West Bank and Gaza settlers, who in most cases were religiously Orthodox, had been associated with a small number of right-wing political parties that frequently splintered and regrouped. Some of these parties were exclusively religious in orientation while others appealed to secular voters, too, but none had much influence in the Knesset – in which, even when included in ruling coalitions, they were insufficiently indispensable to press home their demands. Thus, in recent months, the small National Religious Party and Israel Home Party both have quit Mr. Sharon’s coalition, unable to deter him from his planned pullout from Gaza.

All this led Mr. Feiglin to a new conclusion: If the small parties of the religious and semi-religious right couldn’t change the course of the Likud, their natural ally, from without, why not change it from within? In 2002 he joined the Likud and urged other religious right-wingers to do the same, a campaign that he has pressed for the past three years.

By all appearances, this campaign has been highly successful. Although there are no exact figures on how many Feiglinites have signed up for the party, the latter’s 200,000 registered members could by now include tens of thousands of them. The Feiglinites were instrumental in swinging last May’s Likud referendum against the prime minister, and they have already elected some of their ranks to the Likud’s Central Committee, where they were among the noisiest backers of the “rebels” defeated in this week’s elections.

There was a time when such a development might have seemed good political news. Ever since the establishment of the Jewish state in 1948, it has been repeatedly observed that the proliferation of small parties, particularly ones with religious agendas, has had negative effects. It has weakened the larger parties, led to the politicization of religion, prevented the separation of synagogue and state, and turned the national budget into a schmaltz barrel for the subsidization of religious institutions. How much better it would be, the conventional wisdom went, if religious voters could be persuaded to support major parties that might defend their interests without being narrowly sectorial.

The infiltration of the Likud by the Feiglinites, however, is an unwelcome development. Although there are may be obvious parallels between it and, say, the new activism of fundamentalist Christians in the Republican Party in America (and who, really, would want to see a separate Evangelical Party in America?), there is one fundamental difference. America’s politically activist Christians are focused on a domestic agenda; they may think they are performing God’s will by pushing this agenda, but they understand that they have to push it by rational means and they do not, apart from small groups of End-of-Dayers, believe they are actors in a divine eschatological drama.

Not so the Feiglinites. Many of them are true messianists who are convinced that the retention of the entire land of Israel is part of God’s plan for the Jewish people and the world, and that there is no need to think rationally about how such a plan can be realistically implemented because God will take care of all problems in due time. All Israel has to do is hold on to every inch of sacred ground and make no concessions to the Palestinians; the rest will be arranged by the will of Heaven.

Political messianism, which absolves the faithful of the need for hard political thinking, has always been a disastrous force in Jewish history. There is a danger of its becoming so again. Confined to the fringe parties of the far Right, the Feiglinites are a containable contagion. As infiltrators into the Likud, a nationalist party that has always put realistic principles first, they can leverage Israeli politics in an irrational direction. This week they and their supporters were beaten back. One must hope that their defeat was not just temporary.

Mr. Halkin is a contributing editor of The New York Sun.