Astronomical charts may also have helped determine the timing of the Heaven's Gate suicides. They apparently began on the weekend of March 22-23, around the time that Hale-Bopp got ready to make its closest approach to Earth. That weekend also witnessed a full moon and, in parts of the U.S., a lunar eclipse. For good measure it included Palm Sunday, the beginning of the Christian Holy Week. Shrouds placed on the corpses were purple, the color of Passiontide, or, for New Agers, the color of those who have passed to a higher plane. The Heaven's Gate philosophy added its astronomical trappings to a core of weirdly adulterated Christianity. Then came a whiff of Gnosticism, the old heresy that regarded the body as a burden from which the fretful soul longs to be freed. From the time of St. Paul, some elements of Christianity have indulged an impulse to subjugate the body. But like Judaism and Islam, it ultimately teaches reverence for life and rejects suicide as a shortcut to heaven.

The modern era of cultism dates to the 1970s, when the free inquiry of the previous decade led quite a few exhausted seekers into intellectual surrender. Out from the rubble of the countercultures came such groups as the Children of God and the Divine Light Mission, est and the Church of Scientology, the robotic political followers of Lyndon LaRouche and the Unification Church of the Rev. Sun Myung Moon. On Nov. 18, 1978, the cultism of the '70s arrived at its dark crescendo in Jonestown, Guyana, where more than 900 members of Jim Jones' Peoples Temple died at his order, most by suicide.

Since then two developments have fostered the spread of cultism. One is the end of communism. Whatever the disasters of Marxism, at least it provided an outlet for utopian longings. Now that universalist impulses have one less way to expend themselves, religious enthusiasms of whatever character take on a fresh appeal. And even Russia, with a rich tradition of fevered spirituality and the new upheavals of capitalism, is dealing with modern cults.

Imported sects like the Unification Church have seen an opening there. Homegrown groups have also sprung up. One surrounds a would-be messiah named Vissarion. With his flowing dark hair, wispy beard and a sing-song voice full of aphorisms, he has managed to attract about 5,000 followers to his City of the Sun. Naturally it's in Siberia, near the isolated town of Minusinsk. According to reports in the Russian press, Vissarion is a former traffic cop who was fired for drinking. In his public appearances, he speaks of "the coming end" and instructs believers that suicide is not a sin. Russian authorities are worried that he may urge his followers on a final binge. In the former Soviet lands, law enforcement has handled cults in the old Russian way, with truncheons and bars. Some have been banned. Last year a court in Kiev gave prison terms to leaders of the White Brotherhood, including its would-be messiah, Marina Tsvigun.

The second recent development in cultism is strictly free market and technological. For the quick recruitment of new congregations, the Internet is a magical opportunity. It's persuasive, far reaching and clandestine. And for better and worse, it frees the imagination from the everyday world. "I think that the online context can remove people from a proper understanding of reality and of the proper tests for truth," says Douglas Groothuis, a theologian and author of The Soul in Cyberspace. "How do you verify peoples' identity? How do you connect 'online' with real life?"