JERUSALEM — When "Samson" arrived at the Western Wall several years ago and insisted on moving a large stone that he believed was misplaced, Israeli police were not terribly surprised.

The muscular Canadian tourist who believed he had become the famed strongman of the Bible was turned over to Kfar Shaul, a Jerusalem psychiatric hospital that has hosted countless prophets and many messiahs.

About 100 tourists succumb each year to the so-called Jerusalem Syndrome, a psychiatric disorder in which visitors are swept away by the power of Jerusalem and the Holy Land. Like Samson, most are sent home without causing any damage.

But between Easter 1999 and Easter 2000, Israel expects at least 4 million tourists — twice as many as during a typical year. And many more than usual will be religious pilgrims.

Authorities fear that among them will be dangerous visitors, and even a few apocalyptic groups that may try to bring about the end of the world.

Warning bells are already ringing. Earlier this month, Israeli police arrested members of the Denver-based apocalyptic cult Concerned Christians. They were suspected of planning violent actions in the coming year in order to bring about the second coming of Jesus.

Three members of the cult were detained for questioning, and eventually all 14 were deported back to Denver. The cult's leader, Monte Kim Miller, is believed to be dangerous and hiding in Britain.

In another incident in October, a deranged tourist attempted to set fire to an Egged bus in Jerusalem.

"During the millennium, many will arrive full of religious fervor, and the combination of mentally unstable people and religious faith is extremely dangerous," said Yair Carlos Bar-El, a psychiatrist in Jerusalem who has conducted an extensive study on the Jerusalem Syndrome.

According to Bar-El's still unpublished study, the syndrome is a "unique psychotic state" caused by Jerusalem's special place in the hearts of people of all faiths across the globe.

"When people dream of Jerusalem, they do not see the modern, politically controversial Jerusalem of 1998," he writes, "but rather, the City of David, the City of Jesus, a Gateway to Heaven, God's dwelling place, the place where Messiah will reveal himself or the place where Jesus was resurrected and will, one day, reappear."

Those emotions apparently can spark extreme psychotic reactions. Some tourists convince themselves they are biblical figures. Others believe they must carry out a mission to bring about a miraculous event.

Most people who catch the Jerusalem bug were already mentally unstable when they arrived in Israel, Bar-El said. Christians and Jews are equally susceptible.

In 42 recorded cases, however, perfectly normal visitors were overwhelmed during their stay. Forty of them were Protestants, who are expected to make up the bulk of millennial pilgrims.

A number of Christian groups reject the possibility of potential threats. They insist that the vast majority of visitors will be peace-loving believers seeking a spiritual experience in the place of Jesus' birth.

"We have to use the year 2,000 the best we can to get a sober, solid biblical message out," said David Parsons, spokesman for the International Christian Embassy in Jerusalem, which represents evangelicals across the world.

"In simple terms, the Christian Embassy does not assign any prophetic significance to the years 2000 or 2001…We see no scriptural or other basis for giving these coming two years any inordinate eschatological significance, though they do have symbolic value.

"We know of no other accepted, mainstream evangelical Christian leader or ministry who has made a distinct connection between the Christian belief in the return of the Lord and the year 2000."

According to many Christian scholars, Parsons said, Jesus was actually born in the year 4 or 5 BCE, which means that the second millennial year was actually in 1996.

But on the Mount of Olives, a small group of born-again believers is already waiting to greet Jesus when he returns. If their savior does not arrive on schedule, Bar-El said, such groups could decide they must take action to help him come.

Millennium watchers say some extremist groups may even try to spark the Armageddon by destroying the Al-Aksa Mosque, an Islamic holy site located on the Temple Mount in Jerusalem's Old City. If that would happen, a holy war of huge proportions could ensue.

Gershom Gorenberg, a senior editor at the Jerusalem Report magazine who has researched millennial groups, said a "specific theological school of thought" of pre-millennialists exists that "asserts that the Temple must be rebuilt as part of an `end times' scenario."

The "only problem," he said, "is there is no Temple there."

Which is why some of those groups have a keen interest in fringe, messianic Jewish sects that are planning to rebuild it.

They already have role models for creating chaos.

Michael Rohan, a Christian fundamentalist from Australia, set fire to the Al-Aksa Mosque in 1969. He wanted to rebuild the ancient Israelite Temple, and then destroy it to spark Armageddon and the resurrection of Jesus.

And Alan Goodman, an American Jewish immigrant to Israel, opened fire on Muslims at the Temple Mount in 1982, killing one Palestinian and injuring four.

Both Rohan and Goodman were clinically diagnosed psychotics.

Today, with the fate of the politically sensitive Holy City up for grabs in the final-status talks between Israel and the Palestinian Authority, such an attack could turn into the Jewish state's worst nightmare.

"It is now possible for people who want to bring about the end of the world to bring it about, and people behave very strangely under millennial circumstances," said Richard Landes, a professor of medieval history who heads the Center for Millennial Studies at Boston University.

He said it is "extremely difficult to gauge" just how many people are coming to Jerusalem with apocalyptic ideas because most people don't admit how apocalyptic their views are.

Since many religious pilgrims expect something dramatic to happen, he adds, they will be "extremely susceptible" to apocalyptic rhetoric during their stay.

Landes, speaking at a recent symposium on the subject in Israel, added some historical context to his predictions.

An Orthodox Jew who has studied the last 1,000 years of Jewish-Christian relations, he said that in the year 1033 — the 1,000th anniversary of Jesus's crucifixion — hordes of people came to Jerusalem to mark the event, and many refused to leave.

That, he suggested, could repeat itself now, at least to some extent.

Since there is a dispute about whether the new millennium arrives in 2000 or 2001, Landes said, the pilgrims who come next year to find that "nothing" apocalyptic has occurred will become very anxious and explain it away by noting that the new millennium will actually start in 2001.

"They will suffer cognitive dissonance from the conflict between their expectations and reality; some will lose faith or convert to another religion. The phenomenon will extend over two years at least."

Israeli officials say they are beefing up security and preparing psychiatrists near Christian holy sites in Jerusalem, Nazareth and Tiberias — three expected trouble spots.

Israeli and Palestinian health officials are even working together to head off problems in Palestinian-controlled Bethlehem. But strategic planning remains difficult because nobody is quite sure what to anticipate.

"That's the big problem — nobody wants to prophesize," said Michael Dor, an Israeli Health Ministry official who participates in an Israeli government committee preparing for the millennium.

However, Dor adds, one thing is certain.

"We don't want to hospitalize crazy people from all over the world. As soon as someone is diagnosed, we will send them home as quickly as possible and the state of Israel will foot the bill."