For decades, Saudi Arabia’s ruling family has lent political and financial support to the country’s most fanatical Muslim clergy. The clergy received money to infest the world with their vision of violent jihad; the Al Sauds received religious support for their claims to absolute power. It has been a good marriage — but now the jihadi chickens have come home to roost.

Last week, the Saudi government rounded up 172 men on charges of plotting to assassinate public figures, blow up oil refineries, and fly airplanes into buildings. Quite a few of them turned out to be veterans of jihad in Iraq, where the same Saudi government had sent them to kill Shiite Muslims. Another 136 Saudis were arrested in a similar sweep six months ago, and more will follow.

Though the Saudi government calls them “deviants” today, the royal family used a more complimentary term when encouraging them to kill Shiites in Iraq, Russians in Afghanistan and Chechnya, Serbs in Bosnia, and Christians and Jews in Israel and the West: “heroes of the jihad.”

Confusing? Not really. As part of their pact, Saudi royalty expects the clergy to keep the jihadists in line on their home ground. The Al Sauds have no compunction about exporting fanaticism and its inevitable violence but appear to have forgotten a central maxim for dealers of such volatile compounds: Pushers can’t be users.

During the past 50 years, the Saudi clergy has infused a jihadi ethos into the country’s mosques, schools, universities, and press — and, as a result, the daily lives of Saudi citizens. Today, factories, offices, even passport checkpoints come to a halt several times a day for obligatory prayers. People are flogged for eating during Ramadan.

So it was only a matter of time until there was a jihadist explosion at home, which arrived spectacularly in 1979 when a Saudi by the name of Juhayman al-Otaiba and 400 followers stormed the Grand Mosque of Islam’s holiest site, Mecca, and held it for three weeks. Schooled in the mosques of Mecca and Medina, Otaiba and his cohort protested that Saudi Arabia was not Muslim enough and demanded the departure of the royals.

In the end, the royal family imported “infidel” commandos from France who ended the occupation at the cost of hundreds of lives. But throughout, a substantial portion of the Saudi religious establishment quietly supported Otaiba’s siege.

There have been many other defections since. The most famous is Osama bin Laden, a scion of a fabulously wealthy Saudi business empire whom the Saudi government sponsored in the fight against the Soviets in Afghanistan but whose Al Qaeda movement has since turned against the Saudi royals.

Yet even as the system breaks down, its supporters resist reform. To this day, worshippers in mosques and students in school hear preachers and teachers characterize Shiites as apostates and Christians and Jews as monkeys and pigs. The royal family continues to wear European-tailored suits and a smile abroad and flowing white robes and a stern demeanor at home. But in an age of globalization and the proliferation of images on the Internet, this sort of schizophrenia no longer works: Even the best Muslim will always face a purer Muslim who wants to replace him.

Last Monday, a 10-week farce dubbed an experiment with electoral democracy ended in Saudi Arabia with the choice of several municipal councils. It wasn’t an election in any sense. No women could vote, and the government appointed half the members of each council. Still, voters going to the polls used their cell phones to call their preachers to ask if it would be a “sin” to vote for a candidate they favored.

All those who finally won were part of a so-called Golden List vetted by the clergy. A Jeddah businessman who lost out to the religious slate, Muhammad Dardeer, lamented the strength of such religious fanaticism in an April 24 Washington Post story. “I’m fed up [with] listening to the TV — haram, haram, haram!” Mr. Dardeer told the Post, using the Arabic word for acts forbidden by God and Islam. “I am a Muslim. I have it in my heart. Now, I want to develop my country.”