David Ray Griffin ends a 15-city speaking tour with a date in Cambridge.

David Ray Griffin is a theologian and educator who may be most famous — or notorious — for his belief that the Bush administration let the terrorist attacks of Sept. 11, 2001, happen for political ends. He’s explored the idea in such books as “The New Pearl Harbor Revisited: 9/11, the Cover-Up, and the Exposé” and “Debunking 9/11 Debunking: An Answer to Popular Mechanics and Other Defenders of the Official Conspiracy Theory.”

He hasn’t been much more cozy with the Obama administration, which he says tries to undermine questioners of the official 9/11 narrative.

Despite publishing two books on the topic last year, Griffin seems to be moving beyond a focus on the attack itself. His talk Saturday at Harvard Epworth Methodist Church is to ask “Is the War in Afghanistan Justified by the Events of 9/11?

Cambridge is the last stop on a 15-city tour during which he has been unveiling a strategy for opposing the war in Afghanistan in concert with traditional peace and anti-war groups, organizers say, calling it part of Griffin’s “continuing efforts to promote peace and hasten an end to current and future wars.”

The lecture is is at 7 p.m. Saturday at Harvard Epworth Methodist Church, 1555 Massachusetts Ave. There is a suggested donation of $10 for all but senior citizens and students. Doors open at 6 p.m.