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