THERE’S A POPULAR SCIENTIFIC THEORY known as “the butterfly effect,” in which a small insect beating its wings in one corner of the world can start a chain reaction that leads to a hurricane in another. Like bird flu, the butterfly effect appears to have transmuted and taken up residence among humans. Radical Islamists seem particularly susceptible to the virus, as demonstrated by the global controversy over the Danish cartoons of the Muslim Prophet Muhammad. The butterfly effect, Islamist-style, goes like this: An imam flaps the sleeves of his gown in Copenhagen, and five months later angry mobs torch Scandinavian embassies in Damascus and Beirut.

Most of the cartoons, originally published in the Danish newspaper Jyllands-Posten, were mild to the point of timidity. But two caused particular “outrage” among those who like to take their rage outside and get it on CNN as quickly as possible. One showed Muhammad wearing a turban shaped like a ticking bomb, and the other depicted him at the gates of Paradise, frantically informing a freshly arrived batch of suicide bombers that they had “run out of virgins.”

Jyllands-Posten originally commissioned the cartoons to combat Western self-censorship — a noble goal. Its editor (now on a “leave of absence” and, one suspects, a lot of tranquilizers as well) learned that a Dane writing a children’s book about the life of the Prophet could find no one in Denmark willing to illustrate it, almost certainly because every available artist was afraid of being killed if he or she did. It is a well-known fact that most Muslim countries ban pictures of the Prophet in any form, but Denmark is not a Muslim country. At least not yet.

If Danes were once afraid of what The New York Times terms “the general Muslim prohibition” on images of the Prophet, they must be downright terrified now. (The cartoonists, like an increasing number of Europeans who get on the wrong side of Islamists, are in hiding.) Given the furor, is it fair to ask whether, in the future, Danes should also be afraid of “the general Muslim prohibition” on eating, drinking and smoking during daylight hours in the month of Ramadan? Or on pork? Or on baring long, lovely legs during short, precious summers? Will these ex-Vikings eventually be required to refer to Muhammad not only as “the Prophet” Muhammad, but to add “peace be upon him” whenever they mention his name?

In his new book, While Europe Slept: How Radical Islam Is Destroying the West From Within, published by Doubleday, Bruce Bauer provides ample evidence that these questions need to be asked. Here’s a characteristic passage:

“Muslims have a dream of living in an Islamic society,” declared a Danish Muslim leader in 2000. “This dream will surely be fulfilled in Denmark . . . We will eventually be a majority.” AT-shirt popular among young Muslims in Stockholm reads: “2030 — then we take over.” In many places in Europe, agitation for the transfer of sovereignty has already begun. In France, a public official met with an imam at the edge of Roubaix’s Muslim district, out of respect for his declaration of the neighborhood as Islamic territory to which she had no right of access. In Britain, imams have pressed the government to officially designate certain areas of Bradford as being under Muslim, not British, law. In Denmark, Muslim leaders have sought the same kind of control over parts of Copenhagen. And in Belgium, Muslims living in the Brussels neighborhood of Sint-Jans-Molenbeek already view it not as part of Belgium but as an area under Islamic jurisdiction in which Belgians are not welcome.

One can see the beginnings of such movements in the U.S. Last November in New York, a mosque got city permission to celebrate the end of Ramadan in Tompkins Square Park, the secular heart of the ultra-secular East Village, at 7:30 on a weekday morning. Huge loudspeakers were set up, blaring the Islamic call to prayer in piercingly nasal Arabic for about half an hour, sufficient to wake up people a block away. (The East Village is not noted for its early risers.) Handsomely printed signs were posted on the park fence wishing all a Happy Eid courtesy of the Islamic Council of America, Inc. An African-American convert gave a talk about peace and brotherly love, but, predictably, the tone in which he delivered it was hostile and aggressive. Then a prayer service was held by some 200 to 300 men, with a handful of shrouded women marooned pathetically 20 yards behind them. Was this just an innocent little end-of-Ramadan celebration, or the calculated placement of a cultural marker, an initial bid for spiritual and geographic territory of the kind Bauer describes in his book? Most of the early birds out walking their dogs took a studiously “see no evil, hear no evil” approach, but one black teenager, seeing me take notes, winked and said: “They’re plottin’, man!”

Which is hardly an unusual line of thought. A few days earlier I’d paid a visit to a well-educated Indian friend, who works across from a Middle-Eastern restaurant. He complained that Arabs were going in and out of it all day. “Well, what are they doing?” I asked, presuming they were going in and out for the usual reasons: to eat. “What the hell do you think they are doing?” he rebuked me sternly, eyes practically popping out of his head. “They are conspiring to kill Americans!”

So that’s the word on the street in New York, at least on the basis of an unsolicited, highly unscientific poll of two. On the street in London last week, however, there were words that seemed to confirm those New York words, and then some. Placards held up by radical Muslims protesting the Danish cartoons included these charmers: “Europe Is the Cancer, Islam Is the Answer”; “Exterminate Those Who Slander Islam”; “Europe, Take Some Lessons From 9/11”; and “Prepare for the REAL Holocaust.” The joker in the pack (which otherwise seemed to be running on the “We will not tolerate humor” political platform) held up a sign saying “Freedom of Speech Go to Hell!” Maybe that was Ali G.

None of the protesters was arrested, despite all the hate-crime laws on the books. (In January, a student at Oxford University was taken to court for “homophobic comments” after saying, “Excuse me, do you realize your horse is gay?” to a mounted police officer.)

However, the London bobbies did assure concerned passersby that the hatemongers were being “photographed.” But it was best for passersby not to become overly concerned. When a white, working-class Englishman leaped out of his van to complain about the signs, a copper angrily told him he had “one second” to get back in his van and “get out of here.” But the placard-bearers were allowed to express themselves freely.

In the winter of 2004, while working on a story for this paper, I passed through the Swedish city of Gothenberg. About six months later, in New York, I found myself listening to a sermon in an Upper East Side mosque given by a Gothenberg imam, a Syrian who had also been appointed Mufti (an Islamic scholar who interprets Shar’ia law) for all of Sweden. A brush of the butterfly’s wing. In his impassioned sermon, which was about jihad, this globe-trotting messenger for Allah, who frequently visits California and is known as a moderate, called for the defeat of American troops around the world, which I thought was rather bold of him given that he was standing in the middle of Manhattan. The title of his sermon, he told me when I interviewed him afterward, was “The Ongoing Battle — But Who Is the Enemy?”

The answer to that question seems increasingly to be: “We are.”

Brendan Bernhard’s White Muslim: From L.A. to New York to Jihad, a study of converts in the West, is published by Melville House.

LA Weekly