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