The best Catholic fiction is always written by the worst Catholics. Not the saints in all their virtue—and especially not the heretics, who are willing to undo the whole of Christianity if only their vices can be redefined as secret virtues—but the sinners in all their sin are the ones who are able to create a genuine story. The best Catholic novels seem to be written by those who know, no matter how far they've fallen in faith and morals, that above them or outside them or beyond them lies a truth they did not make and cannot change.
I think this is also true of Jewish writing. The best stuff comes from the sinners.
Rodger Jacobs writes: "The point of the essay I just sent you is that a writer’s view of the world, morality, ethics, and all that jazz, is informed by the religious doctrine one adheres to, whether one later eschews it or continues to cling to it for faith. The idea is you can never escape your religion."