The Jonestown, Guyana, massacre of 1978 did not kill off religious cults in the United States, according to Rabbi James Rudin.

"As a matter fact, the major cults have been doing well since Jonestown," Rudin said in an interview.

Rudin's analysis obviously will be good news at the headquarters of the Rev. Sun Myung Moon's Unification Church, the International Society for Krishna Consciousness, the Divine Light Mission and the Church of Scientology.

It's bad news for the nation's Jewish community, which has provided those religions with a disproportionate number of their members.

About 3 percent of the U.S. population is Jewish. However, about 10 percent to 12 percent of the Moonies come from Jewish homes. What's more, Jews represent 20 percent of the Hare Krishnas, and as much as 30 percent of the Divine Light Mission's membership.

These figures are cited in a new book, "Prison or Paradise? The New Religious Cults," coauthored by Rudin and his wife Marcia.

As assistant national director of interreligious affairs for the American Jewish Committee. Rudin knows how anxious Jewish leaders are about the vulnerability of their young people.

Several years ago the Rudins started monitoring cult activity and have written a book designed to provide Jewish parents with "constructive ways of countering the cults."

Among other things, the Rudins provide a profile of the kind of young person who is most likely to join a cult.

"It appears that the most vulnerable target group for cult recruitment is the person, young or old, who has made no meaningful connection with an established religion, who is in search of spiritual values and transcendent meaning, who is willing, even yearning for strict discipline and authority, and who may be burdened with guilt about affluence or sex or drugs.

"Such a person may enthusiastically make the sacrifices necessary to maintain the love of the cult leader and of his peers within the group. In an age of dislocation, when everything and everyone seems rootless and in flux, when one's own family is seen as superficial and vapid, one's own religion as irrelevant and relativistic, and society as chaotic and uncaring, the absolute claims, guarantees and promises of cult life are appealing."

Asked what kind of preventive measures parents can take before their sons or daughters become involved in cult activities, the rabbi said: "Parents should recognize the absolute necessity for engaging in God talk with their children. Contrary to what has often been said, this is not a post-religious age. Many young people have a keen interest in genuine conversation with their parents about God."

The rabbi had some advice for rabbis, too. "In synagogue life," he said, "bigger is not better. Smaller is our best hope. Congregations need to provide opportunities for their members to join small face-to-face groups."