Their adventure is now the subject of “The Unbelievers,” a documentary out just in time for Christmas, opening for a week in Manhattan on Friday.

If you think a road trip with a pair of intellectuals wielding laptops is likely to lack drama, you haven’t been keeping up with the culture wars. A reviewer in The Los Angeles Timescalled it “a high-minded love fest between two deeply committed atheistic intellectuals and their rock-star-like fan base.”

The Bing Crosby and Bob Hope of this road movie — alas, there is no Dorothy Lamour — are Richard Dawkins, an evolutionary biologist, recently retired from the post of professor of public understanding of science at Oxford University, and Lawrence Krauss, a cosmologist at Arizona State University. They are among the most outspoken of the “new atheists”: scientists and other intellectuals who have tired of having sand kicked in their faces by the priests and mullahs of the world. So the scientists are indeed mobbed like rock stars at glamorous sites like the Sydney Opera House. Inside, they sometimes encounter clueless moderators; outside, demonstrators condemning them to hellfire. At one event, a group of male Muslim protesters are confronted by counterprotesters chanting, “Where are your women?” In between, there are airports and taxi rides and endless cups of coffee.