The far right usually launches protests outside someone's home in the case of "enemies of Israel" - such as inspectors enforcing the 10-month freeze on settlement construction. But on Saturday night, 15 people demonstrated outside the home of a leading settler rabbi, Shlomo Aviner. They were protesting a recent religious ruling Aviner issued, allowing Jewish couples to use sperm donations from non-Jews for artificial insemination, even if they already have children.

The issue may seem arcane, but it is a symptom of a much broader struggle: over the very nature of religious Zionism.

Aviner, an immigrant from France who lives in the West Bank settlement of Beit El and heads the Ateret Cohanim Yeshiva in the Old City of Jerusalem's Muslim Quarter, may seem like an unlikely standard-bearer for the movement's moderate camp. But his progressive views on women's issues have made him one.

Controversy around him first erupted in 2002, when the daily Maariv published a report accusing Aviner of sexually harassing two women. One of the complainants was Chava Elba, wife of Rabbi Ido Elba of Kiryat Arba, considered one of the most extremist settler rabbis. In the 1990s, for example, Elba published an article about when, in his view, it is permissible for a Jew to kill a non-Jew, according to halakha (traditional religious law ). He was convicted of incitement to racism on account of this article and sentenced to two years in jail.

After the Maariv article was published, Elba - backed by Rabbi Dov Lior of Kiryat Arba and Rabbi Yaakov Yosef (whose father, Rabbi Ovadia Yosef, is the spiritual leader of the Shas party ) - embarked on a crusade against Aviner.

In late 2003, then prime minister Ariel Sharon announced his plan to disengage from Gaza, and Elba's crusade soon became entangled with another issue that split the religious Zionist community: whether religious soldiers should disobey orders to evacuate settlements. Aviner opposed disobeying orders; Elba and his camp favored it.

Elba set up a website, Aviner.net, on which he posted material that he thought constituted evidence of the other rabbi's unacceptable behavior - for instance, about a class for brides-to-be in which Aviner used explicit terms to describe sexual organs and the sexual act rather, than the euphemisms normally used in the religious community, and a tape in which Aviner is heard giving permission to a man to look at pornographic pictures because they help him perform sexually.

Aviner's supporters responded with their own website, Aviner.org, on which they sought to refute what they deemed "slanders, fictions, lies and smears."

Elba also launched a campaign to get a rabbinical court to defrock Aviner, and won a major success in July 2009: The Jerusalem Rabbinical Court, in a 2-1 ruling, forbade Aviner to rule on issues concerning women, and particularly questions of niddah - the rules determining when a post-menstrual woman is allowed to resume sexual relations with her husband - on which Aviner was known for his leniency. However, the court allowed him to continue to issue halakhic decisions on other issues.

Aviner obeyed the ruling, and for a year, it seemed peace had been restored in the religious Zionist world. But last week, war erupted anew over his ruling on artificial insemination. While other rabbis have permitted sperm donations from non-Jews in certain extreme circumstances, a couple who already has children is not considered eligible. Thus Aviner's ruling was ground-breaking.

Placards began appearing in the settlements demanding that Aviner be ousted from the rabbinate, and Rabbi Yaakov Yosef publicly demanded this, after denouncing the ruling for "destroying the fundamental principle of the sanctity of Israel."

Meanwhile, Elba sent a formal request for Aviner's ouster to Chief Sephardi Rabbi Shlomo Amar, and also organized Saturday night's demonstration - which participants promised would become a weekly event.

But Elba acknowledges that so far, he has little rabbinical support. "Many rabbis have told me that if [Aviner] is brought down, it will damage the reputation of the entire religious Zionist movement," he told Haaretz.

Aviner could not be reached for comment.