The death of one man—a controversial Dutch filmmaker murdered on an Amsterdam street by a second-generation Moroccan immigrant—has sent the same sort of shock through the Netherlands as the 9/11 attack did in the United States. Theo van Gogh was shot and knifed to death on November 2 by a young Muslim extremist. A s stomach with a knife promised the same fate to the Somali-born member of parliament who wrote the script for Submission, Van Gogh’s last film, about the abuse of women in the name of Allah.

In this country of 16 million, which has long prided itself on its multiculturalism, some saw the violent act as a repudiation of Holland’s policies of tolerance and acceptance toward its roughly 1.5 million first-generation immigrants, many of whom are Muslims. Now the stock of politicians who preach that “Holland is full” is rising—even as they are forced into hiding for fear of suffering Van Gogh’s fate. “When old lefties cry out for law and order you know something has shifted in the political climate; it is now a common perception that the integration of Muslims in Holland has failed,” writes Buruma, a writer and scholar born in the Netherlands.

The tensions in Holland emanate in part from an influx of immigrants and their interaction with a heretofore generous welfare state, writes Caldwell, a senior editor at The Weekly Standard: “As many as 60 percent of Moroccans and Turks above the age of 40—obviously first-generation immigrants—are unemployed.” But more intense friction is produced by clashing values. In other European countries with large immigrant populations, Islamic radicalism is the concern; in the Netherlands, it’s becoming more common to see Islam itself as the problem.

“Pillarization” is often said to be the controlling principle of Dutch society. For many years its Protestant majority and Catholic minority coexisted peaceably within separate pillars of religiously based schools, newspapers, trade unions, etc. In the 1960s, the cultural revolutions that swept other countries targeted class or the state, but Dutch radicals took aim at church authority. The pillars remain, though largely drained of their religiosity. The Dutch thought “they could build up an ‘immigrant’ or a ‘Muslim’ pillar and then let it collapse into postmodern individualism, following the same historic route that Protestantism and Catholicism had taken,” observes Caldwell. But history is not repeating itself.

A few have argued for years that pillarization and the burgeoning Muslim population are incompatible. Conservative statesman Frits Bolkestein was reviled as a racist when he wrote in 1991 that integration wouldn’t work if fundamental Dutch values clashed with those of immigrants on issues like separation of church and state and gender equality. Now he’s a hero. And before his assassination by an animal-rights activist in 2002, populist Pim Fortuyn won overnight popularity by arguing that the country was in immigrant overload.

But if pillarization is failing, alternatives are elusive. Populist leader Geert Wilders proposes that only non-Western foreigners should be stopped from coming to the Netherlands, but that is “morally hard to condone,” says Buruma. Some Muslims, their mosques targeted for arson, point out that the type of insanity that killed Van Gogh doesn’t have a religious affiliation.

Buruma concludes, “The Dutch prided themselves on having built an oasis of tolerance. Now the turbulent world has come to Holland at last, crashing into an idyll that astonished the citizens of less favored nations. It’s a shame that this had to happen, but naiveté is the wrong state of mind for defending one of the oldest and most liberal democracies against those who wish to destroy it.”