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