“I did not have a ‘religious experience,’ ” Mr. Hitchens writes. “Nothing mystical or inexplicable took place  no trance, no swoon, no vision, no voices, no blaze of light. But I had a sudden strong sense of religion being a thing of the present day, not imprisoned under thick layers of time.”

From there, his return to Christianity is gradual, beginning with a rediscovery of the joys of Christmas, followed soon, on the occasion of his wedding, by the urge to be married in the Church of England. Mr. Hitchens’s catalog of return sounds quite ordered, indeed rational. He reattaches to the rituals of his natal church; he realizes that Christendom helped shore up what was best in old England. Much of “The Rage Against God” is in fact a rage against the forgetfulness of Britons, who no longer know their hymns, their great literature or the heroism of their forefathers who died in two world wars. Having noticed that the secularization of England seems to have coincided with its decline, he becomes alive to serious flaws in the reasoning of atheists, like his brother.

He notices that post-Christian societies, like Russia, where he lived for two years as a correspondent, are coarse and brutal. Of Islam and Hinduism, he says over coffee: “I would certainly say, especially having visited countries where they are broadly practiced, that I think they are inferior to Christianity. They are certainly a heck of a lot better than nothing.”

Whereas Christopher argues, in “God Is Not Great,” that criminal states like Stalin’s were in fact not atheist, but quasi-religious cults, Peter concluded that they were indeed as good as their word, atheist to the core, and that their overthrow of God helped enable their murderous policies.

American readers will notice a lack of enthusiasm in Peter’s Christian apologetics. He proceeds largely from historical, rather than personal, evidence: here are the fruits of Christianity, and here is what one finds in its absence. The narrative is cool, not hot; very English, and not with the pious plain-spokenness of, say, C. S. Lewis’s “Mere Christianity,” but with a kind of stiff upper lip, as befits a man sent to boarding school when he was 7. The case for God is built slowly and rationally  as he makes clear, “no trance, no swoon, no visions.”

The Sunday morning we meet, Mr. Hitchens has just bicycled four miles to an Anglican service in a nearby village, the closest church he can use Cranmer’s 1662 Book of Common Prayer. His wife, he says, is with their young son at a “happy clappy service” that is, he confesses ruefully, a bit better for young children. “My wife takes him there so he won’t think church is a place that is only a third full.”

At coffee, I tell him that his book seems to have a strange lack of evangelism. He explains, to my surprise, that he is not seeking converts.