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