Anno Dracula is based on an alternate history where Dracula isn’t killed by Van Helsing but instead kills Van Helsing and marries Queen Victoria, ushering in a new reality where vampires and humans live together in a kind of totalitarian regime.
When Jesus was on the cross the soldiers mocked him, saying things like, “You saved others, but you can’t save yourself. Come down off that cross if you’re really God.” A great novel could explore what would have happened if Jesus did come down off of the cross.
Similarly to Anno Dracula, you could write the whole story and never really see Jesus. You would just see the effects of what life was like now that Jesus had played his hand.
Jesus gets off the cross, and legions of angels show up. The Sanhedrin, Pharisees, and the Romans are all obliterated in one second. Herod pays homage, and Jesus kills him with the terror of his holiness. Jesus takes up residence in the temple. The story would be all about how horrible it would actually be if God, instead of being a God of self-sacrificing love, became a God of dominance, control, and demonstrations of power. That’s what Christians often say they want. They want Jesus to show up and kick ass and take names. But if it really happened, it would be terrible.