Banishers: Ghosts of New Eden

2 Endings in 1.5 Playthrough:

To be on the safe side and avoid triggering any other endings: Don't do any haunting case before saving the 2nd promise.

To achieve resurrection: Finish all haunting cases by blaming the living. You can give the ascension/banish to 3 cases but I don't know if more is tolerated.

Step 1: Advance in the story to the choice of promise to Antea and choose resurrection.

Step 2: Advance in the story to the 2nd promise (choice that arrives on our 2nd visit to the witch's island).
Make a save before the 2nd promise.

Step 3: Confirm the resurrection promise, clear all haunting cases by blaming the living and finish the game (Resurrection Achievement).

Step 4: Reload the savegame before the 2nd promise, change your mind about ascension (no need to do the haunting cases) and rush to the end of the game. (Ascension Achievement)

Note 1: I got the ascension having done only 1 case of haunting by blaming.
In the main quest I blamed 2 times (forest + mountain) before the 2nd promise and I spared Fairefax Haskell.

Warning: For the haunting case concerning Hugh Batcheler, if you blame him, you won't have access to the quest to collect the 15 bibles and you won't be able to complete the achievement.
You must ascend/ban the ghost.