Here is the full list of all 19 Demonologist achievements.
Buy the Pub.
Play on the Kurosawa House map
Buy the Lighthouse.
Successfully joined the "family."
Purchase Two Crucifix
Exorcise the ghost in the Bedlam
Play on the Hospital map
Play on the Bedlam map
Exorcise the ghost 5 times.
Correctly identify the ghost 3 times.
Play on the Abandoned House map.
Correctly identify the ghost once.
Exorcise the ghost once.
Die once.
Take Two Photos Of The Ghost.
Revive your friend with a Tarot Card.
Read EMF Level 5.
Play on the Cyclone Street map.