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