Even if God does exist, James Morrow probably has nothing to worry about. In His infinite wisdom, He’ll want to keep this hilarious old atheist nearby.

Now 67, Morrow has been writing satiric science fiction and historical novels for almost 35 years. A rationalist with a cerebral/silly sense of humor, he crucifies what he considers the absurdities of religious belief. Whether now or long ago, his stories focus on places where tectonic plates of thought grind against each other.

His latest novel, “Galápagos Regained,” locates the conflict between faith and science in the mid-19th century, when traditional clerics were running out of cheeks to turn. Though now long-forgotten — because Morrow made it up — in 1848 the Shelley Society of London proposed a competition “whereby they would award an immense cash prize of £10,000 to the first scholar, scientist, or theologian who could prove, or disprove, the existence of God.”

Of course, for Morrow, a theologian has a snowball’s chance in hell of winning this Great God Contest. But it wouldn’t be fun if the outcome were too obviously predestined, and so he brings on a range of theist and atheist presentations, all comically pompous and all damned, one by one, by the faithful or faithless Bysshean judges. In some ways, this early part of the novel is a Victorian version of Rebecca Newberger Goldstein’s “36 Arguments for the Existence of God,” a survey of the Argument from Evil, the Cosmological Proof, the Unmoved Mover, etc., etc., gloria in excelsis deo. But Morrow has something much more peripatetic — and ridiculous — in mind.

The heroine of “Galápagos Regained” is a young actress named Chloe Bathurst, another of Morrow’s brilliant female characters caught in the confluence of intellectual revolution. Expelled from the theater for inspiring communist rabble rousers, Chloe is forced to abandon her art and take a job as a nanny with Emma and Charles Darwin. In this delightful re-creation of the naturalist’s home, we see Darwin content to tend his menagerie of exotic animals, and keep safely stuffed away in a drawer the discovery that will one day rock the world. But Chloe sees the opportunity of a lifetime in Darwin’s research. Desperate to buy her father out of debtor’s prison, she purloins a copy of his thesis and sets out to win the Great God Contest herself.

In the novel’s fictional competition, a London society offers “an immense cash prize of £10,000 to the first scholar, scientist, or theologian who could prove, or disprove, the existence of God.” (St. Martin's)

Naturally, this mercenary scheme is complicated by one monkey wrench after another, as told in Morrow’s Victorian-inflected voice. (Everything here happens “whilst” something else is happening.) To make her argument against God convincing, Chloe must first travel to the Galápagos Islands to collect living demonstrations of her (Darwin’s) theory.

You can’t possibly anticipate how this crazy story evolves. Chloe and her little gang of disciples — including a minister secretly set to thwart their mission — move across the world by land and sea and sky. (Do you know how many swim-bladder fish it takes to make a hot-air balloon? You will learn!) Glittered with allusions to Herman Melville, Joseph Conrad and Jules Verne, Chloe’s journey is a compendium of every possible disaster, leavened with a Gilbert & Sullivan sensitivity. Morrow writes, “Although she’d endured numerous stage-bound aquatic catastrophes, most memorably the tidal wave that had drowned blind Nydia in ‘The Last Days of Pompeii,’ nothing had prepared her for the present spectacle.”

They’re attacked by condors and pythons and piranhas, oh my! Across the seas, up the Amazon, through the archipelago, Chloe and her friends confront cruel rubber barons, bloodthirsty cannibals and kooky Mormons. In a rare moment of self-doubt, Chloe wonders, “Had she bitten off so large a portion of presumption that even Jonah’s whale would not attempt to chew it?”

With its breathless, loopy plot — as much a parody of 19th-century romance as an exemplar of it — “Galápagos Regained” reflects the endless, ever-evolving variety of life itself. And, as he’s done before, Morrow crossbreeds his fictional characters with real-life figures, from Gregor Mendel and Alfred Russel Wallace to Rosalind Franklin. Yes, time and logic offer no barriers to this author. He’s working in the satiric tradition of Mark Twain, who also couldn’t resist some cheap shots at Mormons. A late scene involving a jury of convicts impaneled to rule in a blasphemy trial involving Noah’s Ark could have jumped out of “A Connecticut Yankee in King Arthur’s Court.” One straight-faced bit of silliness topples over into another, cutting with surprising sharpness to the bone of human nature.

But despite the thousands of miles this story traverses, its internal voyage is just as vast and unexpected. Chloe — so bold and magnetic — constantly adapts in response to her environment. “It was a simple matter,” Morrow writes, “of being shrewder than King Cecrops, more resourceful than Lord Poseidon, and as wise as Lady Athena.” As a great actress, Chloe sets out willing to perform whatever script the Great God Contest requires to win, but along the way, she grows invested in the truth as never before. If only the truth would stay fixed. Despite Morrow’s confirmed atheism and his gleeful mockery of religious fundamentalism, in Chloe he’s created a character capable of surprising spiritual mutation.

Having seen and survived so much, can she argue that everything — every gorgeous, dazzlingly inventive creature — is merely “the accidental efflux of an indifferent machine”?

That’s a question for the Shelley Society to decide, but the creator of “Galápagos Regained” has revealed a divine comedy.

Charles is the editor of Book World. You can follow him on Twitter @RonCharles.

GALÁPAGOS REGAINED

By James Morrow

St. Martin’s. 477 pp. $28.99