Newman, Kim, and Eugene Byrne. "The Wandering Christian"
Divergence: 312 CE
What if: Constantine was defeated by Maxentius at the Milvian Bridge after his army panicked, making Christianity a laughing-stock of a religion.
Summary: In 4759 (999 CE), the Wandering Jew/Christian tells the story of his life, from 30 CE Jerusalem to Persian-besieged Jewish Rome.
Published: In Tales of the Wandering Jew (ed. Brian Stableford), Daedalus 1991 (0946626715); and The Mammoth Book of Alternate Histories (eds. Ian Watson and Ian Whates), q.v.
Web link: Newman & Byrne Messed-Up History Experience