HOLY TERROR Inside the World of Islamic Terrorism By Amir Taheri Adler & Adler. 332 pp. $19.95

HOLY TERROR tells Iranophobic Americans what they probably want to hear about Islamic fundamentalism these days. The mullahs of Iran are power-mad killers, driven by a brand of Islam that is bloodthirsty and intolerant at its core. They want to destroy the West -- Christians, Jews, atheists -- and especially Americans. They are, in short, ruthless enemies, who regard our gestures of friendship as a sign of weakness.

Readers looking for a more restrained and careful discussion of radical Islam should probably look elsewhere, for Holy Terror is just what its title suggests: a polemical layman's guide to Islamic terrorism. The author is an exiled Iranian journalist, and his book is "journalistic" in the best and worst senses. It is readable, but not entirely reliable. Indeed, much of Holy Terror reads like a newsmagazine cover story. It has the same tendentious style, the same rush of "inside" details about terrorist training camps and suicide bombers, and the same maddening lack of attribution for key bits of information.

Amir Taheri's theme is that Islamic fundamentalism is an essentially totalitarian ideology that at various moments in history has exploded with rage, intolerance and violence. Islam has many less-threatening faces. But according to Taheri, "Radical Islam is bound to end in terrorism." It is a religion that in its extreme fundamentalist form rejects the boundary between secular and religious power, and Taheri argues that its leaders should in fact be regarded as calculating and cynical politicians, rather than as holy men.

Holy Terror is organized as a series of case studies that seek to document Taheri's thesis. He argues that terror has been a weapon since the earliest days of Islam, when three of the four caliphs who succeeded the Prophet Mohammed were assassinated. He assembles a group portrait of some of the Islamic cutthroats and fanatics who have emerged since: from the 11th-century brigand, Hassan Sabah, whose hashish-crazed followers murdered their enemies with poisoned knives; to the 20th-century Moslem Brothers of Egypt who, according to Taheri, so admired fascism that some of them believed Mussolini was really an Egyptian Moslem named "Musa Nili" (or Moses of the Nile) and that Hitler had secretly converted to Islam and taken the name "Hayder." Taheri revels in these examples of Islam at its worst, and he gives scant attention to the counterevidence that paints Islam as a multi-faceted religion, rather than a car bomb ready to explode.

BY THE time Taheri's narrative reaches Iran's Ayatollah Khomeini, the reader may feel ready to surrender to the relentless forces of Holy Terror. Reading page after page about these odious Islamic radicals is a bit like watching the crowds of chanting Iranians on Nightline during the Iran hostage crisis: It's appalling, mesmerising, enervating -- and ultimately, an exercise in self-flagellation.

Details about Khomeini's terrorism crowd the latter half of the book: a list of 16 terrorist training camps inside Iran that describes their precise locations and functions; details of a $400 million terrorism slush fund supposedly distributed in 1983 by Iran's ambassador in Damascus; a list of the members of the High Council of Islamic Jihad for Lebanon, which purportedly supervises terrorism and hostage-taking in Lebanon. Taheri provides a virtual order of battle for Iranian-backed terrorism.

The problem for the careful reader is assessing how much of Taheri's information is reliable. Checking his order of battle is difficult, because many of his assertions lack clear documentation.

For example, a chapter on the Iranian-born Lebanese Shiite leader Musa Sadr (who, according to Taheri, came to Lebanon in 1961 with a subsidy of more than $1 million a year from the shah's secret police, Savak) includes a fascinating account of Musa Sadr's mysterious disappearance in Libya in 1978. Taheri says that after Musa Sadr quarreled one night with Col. Gadhafi, the volatile Libyan leader muttered to a military aide the Arabic word, "khalas," which means "Enough." The military aide thought he was hearing an order to kill Musa Sadr and promptly did the dirty deed, says Taheri. But when you turn to the footnotes to see the authority for this juicy account, it turns out to be a 1980 article in the French magazine Jeune Afrique, which is hardly an unimpeachable source.

Some of Taheri's material seems highly dubious. For example, he provides a sensational account of the death of one of the Beirut hostages, former CIA station chief William Buckley. According to Taheri, Buckley was taken to Iran and "died under torture after being removed to the Caspian resort of Chalus, where he was held at the former Hyatt Hotel which had been converted into a prison for foreign hostages." The problem with this account is that several of the other hostages who were eventually released say they heard Buckley's screams as he was dying -- in Lebanon. Other mistakes, from erroneous dates to eccentric spellings, mar Taheri's book.

After painting such a sensational portrait of radical Islam, Taheri reaches a suprisingly restrained and sensible conclusion. Islamic fundamentalism will eventually backfire, he contends. Indeed, by trying to distance itself from the "satanic" modern world, "the Party of Allah has done more to push Islam into that world than any other movement in Islam during the past 150 years." The backlash has already begun in Sudan, Egypt and the West Bank, says Taheri.

While we're waiting for radical Islam to spend its energy, concludes Taheri, we should be true to our Western values and avoid Rambo-style tactics or a "new, computerized version of the Crusades." That's sound advice, especially for some overeager readers of books like Holy Terror, who may imagine that it's time for Uncle Sam to get in the jihad business.

David Ignatius, associate editor of The Washington Post, is the author of a novel about terrorism and the CIA, "Agents of Innocence."