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