The plot involves the disappearance of a brass crucifix from a down-at-the-heels Manhattan Episcopal church ministered by Thomas Pemberton, a doubting, ponytailed relic of the ’60s. When the cross turns up on the roof of the Synagogue for Evolutionary Judaism, Pemberton sees solving the mystery of how it got there as an opportunity to renew his flagging faith. And Pem’s writer friend Everett recognizes a premise for his next novel.

“City of God” takes the form of Everett’s workbook, into which he, the novelist-within-the-novel, dumps everything from barroom theological debates with Pem to an unearthed child’s account of the horrors of the Kovno ghetto under Nazi occupation. The notebook conceit allows Doctorow to marshal the evidence he needs to bring Christianity into the docket for not suffering the same kind of crisis that the Holocaust wreaked on Judaism. As Pem asks his flock, “what mortification, what ritual, what practice might have been a commensurate Christian response to the disaster”? Although the crucifix on the synagogue roof is a clue, Doctorow’s probing novel leaves open the question of exactly where, between a cold ocean hell and Pem’s starting over, true atonement lies.