“Not by me,” Dawkins replied before providing his standard explanation—a supreme being is possible but highly improbable—which led a London newspaper to proclaim that the world’s most notorious skeptic was hedging his bets. Far from it. Dawkins, at 71, remains an unbending and sharp-tongued critic of religious dogmatism. Like any scientist who challenges the Bible and its lyrical version of creation, he spends a great deal of time defending Charles Darwin’s theory that all life, including humans, evolved over eons through natural selection, rather than being molded 10,000 years ago by an intelligent but unseen hand.

Dawkins, who retired from Oxford University in 2008 after 13 years as a professor of public understanding of science (meaning he lectured and wrote books), stepped into the limelight in 1976, at the age of 35, with the publication of The Selfish Gene. The book, which has sold more than a million copies, argues persuasively that evolution takes place at the genetic level; individuals die, but the fittest genes survive. Dawkins has since written 10 more best-sellers, including most recently The Magic of Reality: How We Know What’s Really True. Since 9/11 he has become more outspoken about his skepticism, culminating in The God Delusion, which provides the foundation for his continuing debates with believers. Published in 2006, the book has become Dawkins’s most popular, available in 31 languages with 2 million copies sold. That same year he founded the Richard Dawkins Foundation for Reason and Science “to support scientific education, critical thinking and evidence-based understanding of the natural world in the quest to overcome religious fundamentalism, superstition, intolerance and suffering.” His books have made Dawkins a popular speaker and champion of critical thinking. In March he spoke to 20,000 people at the Reason Rally on the National Mall in Washington, D.C.; a week later he was at Fort Bragg in North Carolina, offering encouragement to the first gathering of atheistic and agnostic soldiers ever allowed on a U.S. military base.

Dawkins lives in Oxford with his third wife, Lalla Ward, best known for her role as Romana on Doctor Who. But he is rarely home for long, and Contributing Editor Chip Rowe had to travel to three cities to complete their conversation. He reports: “Dawkins is a careful speaker with little patience for foolishness (which is everywhere, especially among the faithful and the occasional journalist), but he straightens and his eyes dance when he is asked to explain an evolutionary principle. We met for the first time in Las Vegas at a convention for skeptics. We talked again when he visited New York to lecture at Cooper Union and in Washington, where he spoke at Howard University, checked in with the director of his foundation, thanked its volunteers and visited the impressive human origins exhibit at the Smithsonian’s National Museum of Natural History. During a tour with the exhibit’s curator, Dawkins looked pained anytime he was compelled to chat, glancing furtively at the fossilized eye candy in every direction, including a wall of progressively modern skulls. At one point two young women approached. ‘This is Richard Dawkins!’ one told the other, wide-eyed. I suppose it’s like bumping into Bono at the Rock and Roll Hall of Fame.”

PLAYBOY: What is the A pin you’re wearing?

DAWKINS: It stands for “atheist.”

PLAYBOY: Like a scarlet letter?

DAWKINS: It’s not meant to reflect that. It’s part of my foundation’s Out Campaign. It means stand out and reach out, as well as come out for the beliefs you hold, and give the reasons. It’s a bit analogous to gay people coming out.

PLAYBOY: Although atheists can marry one another.

DAWKINS: True.

PLAYBOY: Is there a better word for a nonbeliever than atheist? Darwin preferred agnostic. Some have suggested humanist, naturalist, nontheist.

DAWKINS: Darwin chose agnostic for tactical reasons. He said the common man was not ready for atheism. There’s a lovely story the comedian Julia Sweeney tells about her own journey from devout Catholicism to atheism. After she’d finally decided she was an atheist, something appeared about it in the newspaper. Her mother phoned her in hysterics and said something like “I don’t mind you not believing in God, but an atheist?” [laughs] The word bright was suggested by a California couple. I think it’s rather a good word, though most of my atheist friends think it suggests religious people are dims. I say, “What’s wrong with that?” [laughs]

PLAYBOY: You’ve described yourself as a “tooth fairy” agnostic. What is that?

DAWKINS: Rather than say he’s an atheist, a friend of mine says, “I’m a tooth fairy agnostic,” meaning he can’t disprove God but thinks God is about as likely as the tooth fairy.