When David Ray Griffin talks about the people behind the terrorist attacks of September 11, 2001, his ideas sound as outlandish and sinister as an "X-Files" storyline. Griffin is a prominent spokesperson in the "9/11 truth movement," which challenges the official conclusions of the 9/11 Commission that the hijackings were masterminded by Osama bin Laden and pulled off by 19 Muslim extremists. Griffin contends not only that the Bush administration knew about the attacks in advance, but also that the plot was orchestrated by top-ranking U.S. government officials. Their intent, he asserts: to provide the necessary catalyst -- like Pearl Harbor for America's entry into World War II -- for U.S. military intervention in the oil-rich regions of Asia and the Middle East.

Griffin, 66, seems an unlikely expert on U.S. intelligence or military affairs. Before joining the ranks of 9/11 skeptics, he spent 31 years teaching theology and the philosophy of religion at the Claremont School of Theology in California. Nevertheless, he has emerged as one of the leading voices in the 9/11 truth movement, a point of view that seems to be gaining legions of followers -- or at least selling lots of books.

Griffin is himself the author of several books on 9/11 and its roots in American imperialism, including 2004's The New Pearl Harbor: Disturbing Questions about 9/11 and the Bush Administration, and The 9/11 Commission Report: Omissions and Distortions, published this year. He comes to Vermont next month for speaking engagements entitled, "The Truth Behind 9/11: A Christian Theologian Speaks Out," sponsored by Southern Vermonters for Fair Economy and Environmental Priorities.

Griffin says his theological underpinnings morally compel him and other people of faith to seek the truth behind what really happened on that fateful day four years ago. "[O]ur first allegiance must be to God, who created and loves all people, indeed all forms of life," Griffin writes in the latest issue of the progressive Methodist journal, Zion's Herald. "If we believe that our political and military leaders are acting on the basis of policies that are diametrically opposed to the divine purposes, it is incumbent upon us to say this."

Like many Americans, in the months after 9/11 Griffin believed the United States was experiencing "blowback" from years of meddling in the affairs of other nations. "When a colleague first said that he thought this was an inside job -- he happened to be a British colleague -- my first response was very typical of many Americans. I didn't think that even the Bush administration would do such a thing," Griffin says in a phone interview from his home near Santa Barbara, California. "But then it finally dawned on me that, like other imperialistic nations, we had provoked wars [before] by doing something and then blaming the other side."

Griffin's theories might easily be dismissed as the work of an intelligent and well-intentioned crank -- were they not so intriguing and well-researched. His books and public speaking engagements -- including an address to the National Press Club in Washington, D.C., and another that aired recently on C-SPAN -- draw from such mainstream sources as The New York Times and The Washington Post. They include interviews with FBI agents who claim they approached administration officials just weeks before 9/11 to warn of the attacks.

For example, Griffin points to the spike in abnormal stock-market activity just before 9/11, which U.S. intelligence agencies usually monitor as indicators of an impending terrorist attack. Griffin claims that the days leading up to September 11 saw an unusually high number of "put options" -- market bets that stock prices would drop -- on shares of just two airlines, American and United. The same thing happened with shares of Morgan Stanley Dean Witter, the brokerage house that occupied 22 floors in the World Trade Center.

Griffin also compared engineers' assessments of how the buildings collapsed at Ground Zero with the history of similar steel buildings that had burned. Griffins asserts that the collapse of the Twin Towers as well as World Trade Center Seven -- a 47-story building that was never hit by an aircraft and had fires on just two floors -- were all textbook examples of controlled demolitions.

"High-rise, steel-frame buildings have never -- before or after 9/11 -- been caused to collapse by fire," Griffin asserts. "Such a desperate lie is a sure sign of a cover-up." Nevertheless, he says, the 9/11 Commission Report completely ignored the subject. Likewise, Griffin says, the Commission offered no explanation for why the towers' steel support beams were removed from Ground Zero -- ordinarily, removing evidence from a crime scene is a federal offense -- and shipped to Asian steel mills to be melted down.

Griffin also raises serious doubts that a small cabal of radical extremists had the technological wherewithal to outsmart the sophisticated radar-defense system that protects the Pentagon. How, he wonders, could the most well-defended structure on the planet, which was ringed by anti-aircraft guns and defended by three fighter squadrons at Andrews Air Force Base less than 10 miles away, have been attacked by a lumbering commercial jet flown by an inexperienced pilot? And why were all the surveillance videos of the plane crashing into Pentagon immediately removed and never made public?

Griffin's theories seem to have all the makings of a tightly woven conspiracy theory: They cite hard science, seem plausible enough to fall within the realm of believability and, for true believers, satisfy the worst suspicions about the evils of those in power. But Griffin seems unperturbed by the conspiracy-theory label.

"'Conspiracy theory' has so many connotations," he says. "The tack I take is to say, let's not shy away from the word. Let's just point out that the official story [of 9/11] is the original conspiracy theory. If you want to talk about outrageous, talk about fire bringing down steel-frame buildings for the first time in history. Or Hani Hanjour [the hijacker who reportedly piloted American Airlines Flight 77], who could not even fly a Cessna, flying a Boeing 757 in a magnificent loop down into the Pentagon. You can't get more outrageous than that."

Would Americans accept the idea that the Bush administration is guilty of murder and high treason? A Zogby International poll conducted in August 2004 found that nearly half of New York City residents -- 49.3 percent -- believed that the federal government "knew in advance that attacks were planned on or around September 11, 2001 and that they consciously failed to act." A similar poll, conducted in Canada and Germany last year, found that 15 to 20 percent of their citizens believed that the Bush administration not only had foreknowledge of the September 11 attacks, but actually had a hand in them. No one has yet posed the latter question in the United States.

Griffin hasn't gained much credibility in the mainstream U.S. media. Thus far, no major American newspaper has reviewed his books, though the Los Angeles Times Magazine recently ran a brief interview with him.

Griffin doesn't suggest the mainstream press is deliberately covering up his work. He simply believes they lack the courage to address the issue. "Editors know what their owners will allow and not allow, and if they cross that line, they'll be fired or called on the carpet," he says. "When you're talking about, say, NBC, do you really think that [a network] owned by General Electric is going to expose 9/11 if it was for the global war on terror, which is making GE filthy rich?"

And Griffin's theories about 9/11 -- which, it should be noted, aren't his alone but are shared by other writers across the political spectrum -- might eventually gain traction, like similar theories about the Kennedy assassination.

"Eighty percent of the American people reject the [conclusions of] the Warren Commission, and yet it is not part of the greater public consciousness that forces within our own government were involved in the assassination of Kennedy," Griffin concludes. "The American people have been pretty tolerant of learning that we fixed the intelligence to invade Iraq. But I think the one thing the American people would not stand for is learning that [their own government] arranged 9/11."

He adds, "I can't say I'm optimistic."