In an almost unimaginably perverse way, the attacks of September 11 constituted the greatest religious infomercial the world has ever seen. In the West, Islam went from being a controversial but still rather remote creed to a religion many people couldn’t stop thinking, talking, and writing about. Even in sunny Culver City, a region of Los Angeles so squeaky clean the traffic lights emit cuckoo-clock sounds, Islam is a presence. There is a large, very beautiful mosque (through which one of the 9/11 hijackers is said to have passed), and there is Charles Johnson, editor of the political blog Little Green Footballs, one of the best information sources on the Web for those keeping track of the tentacular, global reach of Islamist ideology and terrorism.

Sitting in a Starbucks cafe, Mr. Johnson looked very much like any other Southern Californian with enough time and money to spend on a bountiful mocha frappucino grande. A pony tail escaped the back of his beige Nike baseball cap, he wore a maroon sweat shirt, blue jeans, and sneakers, and he had just bicycled some 50 miles for exercise – his custom on Saturday mornings. For a former jazz musician and electric guitarist who has played and toured with the likes of Stanley Clarke and Al Jarreau, he seemed decidedly un-laidback, even jittery at times. But then, many of his former jazz world friends no longer speak to him, he suffers from cyber stalkers, and he is drowning in spam – his enemies sign him up for every nitwit Internet product and crass e-mail letter they can find. It’s a tough world out there, particularly when you’re an arty type who has taken a staunchly pro-American, pro-Bush stand.

Mr. Johnson, who is 51, founded Little Green Footballs early in 2001 as an offshoot of his Web-design business. He won’t disclose what those titular footballs mean, saying only that they’re not a drug reference, that they have something to do with a stay in Japan, and that there were “actual little green footballs involved.” Though it is now about the post-September 11 world and the spread of radical Islam in particular, the blog was initially set up as a place to exchange programming information. (The last entry for September 10, 2001, reads, “Here’s a well-executed academic study of where users expect things to be on a typical web page.”) An independent who leaned left, Mr. Johnson was no fan of George W. Bush, and ridiculed the president on his site. But the September 11 attacks changed all that.

“From the very first day we started to get comments from Europeans,” he said, referring to the blog, even though it was largely nonpolitical at the time. The comments were generally along the lines of, “You deserved it,” and Mr. Johnson was shocked. “I’ve spent a lot of time in Europe, I have European friends, but I thought, ‘No one deserves that.’ “

Though he was caught off guard by the European reaction, Mr. Johnson was not entirely surprised by the September 11 attacks themselves. Touring the world as a musician, which he did throughout much of the 1990s, he made a point of reading up on the countries he visited and on world politics in general. “I was aware of Osama bin Laden’s initial declaration of war against America in ’92,” he told me. “So when September 11 came around, I knew right away who had done it – ‘Here it is, bin Laden’s back again.’ I wasn’t surprised. But it was a soul-shaking event.”

It certainly shook Mr. Johnson’s soul, already profoundly scarred by a bitter divorce in the late 1990s. The Web-design venture, which he runs with his brother, Michael, a former dancer who lives in San Francisco, and the blog, which he edits alone, allowed him to immerse himself in work and put his marital woes behind him. So successfully, in fact, that he now takes to the road on his bicycle in order to get away from the blog. By the time he returns, regular visitors to the site are already demanding to know where he is and why he hasn’t posted anything in the last two hours.

On his new CD, “Dear Heather,” the Canadian songwriter Leonard Cohen has a song about September 11 in which he asks, “Did you go crazy / Or did you report / On that day / They wounded New York.” A footnote in the CD’s liner notes informs us that Mr. Cohen is using the word “report” in accordance with the third definition from The American Heritage Dictionary: “To present oneself; report for duty.” It might be said that this is exactly what Mr. Johnson has done with Little Green Footballs. Although it tilts right politically, it provides a cornucopia of information about radical Islam here and abroad that ought to be of use to anyone with an interest in the subject, and Mr. Johnson edits it with intelligence and wit. (“Religion of Peace Kills 14, Wounds 3,” is one of his characteristically cutting headlines.) If you believe that the war on terror is necessary, that the occupation of Iraq is ultimately generous in intent, and that the level of Muslim immigration to the West poses a serious threat, then this is surely a Web site for you.

Mr. Johnson’s political opponents would say that, on the contrary, he is one of those who went “crazy” on September 11 by losing all sense of perspective, while they – clear-eyed and level-headed – have reported for duty by opposing an unnecessary war, adopting a peaceable posture towards the Islamic world, and supporting the presidential candidacy of Senator Kerry. I asked Mr. Johnson if it wasn’t in fact possible that the War on Terror was out of all proportion to the threat. He conceded that he had occasionally wondered if it wasn’t an overreaction, but said he believed the Bush administration had taken the correct course by adopting a long-term view of the situation. “When you see that 19 guys can take jetliners and wipe out two of the biggest symbols in America,” he said, it would be fatal to be passive. “If we let it go, one of those groups is going to have a nuclear weapon.”

Mr. Johnson’s biggest coup so far came when, together with some other bloggers, he exposed the forged documents with which CBS’s “60 Minutes” sought to undermine President Bush’s claim to have served honorably in the Texas National Guard during the Vietnam War. It was Mr. Johnson who, copying the forgery from a PDF file CBS posted on its Web site, retyped the memo using Microsoft Word’s standard settings, and found that his version was identical in every detail to the one Dan Rather claimed had been typed on a manual typewriter some three decades earlier.

As he typed the first sentences and found that the lines were all breaking the same way, Mr. Johnson said he felt chills running down his spine. “In a way it’s bigger than Watergate, because Watergate wasn’t an attempt to influence an election,” he told me, adding that he is still stunned by CBS’s gullibility and ineptness. “It shows you the amount of desperation at work. It overrode all of their journalistic impulses. They lost all their ethics. That’s the big story – they did it because they wanted Bush not to be elected.”

With the enthusiastic backing of his readers (the site averages 60,000 unique visitors a day), many of whom pitch in eagerly by penning hundreds of responses to a single posting, Mr. Johnson writes scathingly about the mainstream media, which he refers to by the derisory acronym “MSM.” He regularly castigates what might be termed the Guardian worldview abroad, and lashes out frequently at “al-Reuters” and other news services for their anti-American biases. (“Who needs Tokyo Rose when we have AP?” he asked recently.) But he relies heavily on the very journalists he castigates, without whose reports he would have little to comment on or criticize.

Like all the best blogs, Little Green Footballs can become addictive, if only because it speaks to its audience much more directly than a general-interest newspaper or magazine could ever do, and Mr. Johnson himself certainly isn’t ready to kick the habit. Recently Al Jarreau called to ask if he was ready to go back on tour. The answer was no.