You can win the game by appeasing both God's and Devil's advocates to let you become a saint (Get both bars on the left to 100%). How quickly you can do that is just based on how you play, but obviously the randomized events will get in your way and make each run at least slightly unique.
The game is intentionally pretty hard. There are also some specific bad events that happen if you have too big of a difference between God's and Devil's reputation so it's recommended to not have a large gap between them if that helps. Balancing this sort of game is very hard for obvious reasons.
Thanks for playing!