I managed to get the ending of the Church of the Chosen Ones. Basicly, you have to let them manage the whole community. You will be given lots of choices during the game, concerning the Church.
I can't explain exactly WHY and HOW this ending triggers, but I'll write every "potential switches" I did , it might help you reproduce this success.
--> The book about zombies wasn't banned
--> Refused to give shelter to the mysterious scientist and the rescapée from the Last Judgement Gang
--> Played on Easy mode, small city map
--> Punish the "heretics"
--> Let the Church turn one of the graveyards into a church
--> Capture the Big Graveyard (the overruned one)
--> Capture the Heliport, and when the quest for the heliport says "blablabla reads, keeps on reading but reads about love-zombies books, should we force her to read repairing helicopters for dummies?" answered NO
--> I had no bars. Maybe alcohol interfered with spirituality? Or whatever this sect might be ...
Good luck. But if you just can't reproduce it, all the endings are on youtube. Even tho they don't have the best quality.
The ending will trigger when the suicide rituals will have reduced your population to the number of THREE. As soon as you click on "End Day", the Church of the Chosen Ones will throw you (well, your character) over the fence, and you will die.
Note that with this ending, you cannot continue playing.