Kuttner, Henry, and C.L. Moore. Beyond Heaven's Gates
Divergence: c 30 CE
Summary: A man and woman fall into a non-Christian parallel run by alchemic priests, who believe our New York is Paradise.
Published: Ace Double #D-69, Ace 1954. Revision of Kuttner's "The Portal in the Picture" (as by Lewis Padgett), in Startling Stories, September 1949; and The Startling Worlds of Henry Kuttner, Popular Library/Questar (0445203285).