"The rabbi presented him with a children’s book titled 'Jewish Traditions and Customs,' intended to discourage Villanueva from any notion of converting."

"'The book would make clear who was Jewish and who was not, why a highland Peruvian, a cholo, was not, and could not be, Jewish'.... But when Villanueva opened the book, what he found was a revelation. It described precisely the way he and his followers were already living, and he arrived home delighted, the mystery solved at last. Guess what, he told his congregation: They were Jewish! They’d been Jews all along!... Is it a matter of bloodlines? Tradition? Observance? Faith? But Villanueva was neither aware of nor interested in religious gatekeeping.... In one memorable scene, Villanueva and his congregation return to the rabbi in search of circumcision (not the metaphorical kind) but are turned away; their only other option is a surgeon who will perform the procedure for the hefty sum of $60 apiece. One imagines that many men would simply (and perhaps relievedly) abandon the enterprise at this point, but Villanueva would not be deterred: Three years later, he and a dozen followers were back with cash in hand."

From "One Man and His Followers Sought Salvation. Did It Exist? 'The Prophet of the Andes' tells the story of Segundo Villanueva, a quixotic spiritual seeker who led hundreds of followers from Peru to Israel" (NYT).

Here's the book: "The Prophet of the Andes."

ADDED: That last link goes to Amazon, where there is this blurb from Judith Thurman: "If Gabriel García Márquez had written the Old Testament, it might read like Graciela Mochkofsky's staggering true account of a humble Peruvian carpenter's spiritual odyssey from a shack in the Andes, via the Amazon, to the Promised Land of Israel with a community of devoted followers."