Here is the full list of all 19 Demonologist achievements.
Die once.
Play on the Cyclone Street map.
Correctly identify the ghost once.
Play on the Abandoned House map.
Read EMF Level 5.
Exorcise the ghost once.
Exorcise the ghost 5 times.
Purchase Two Crucifix
Buy the Pub.
Buy the Lighthouse.
Play on the Hospital map
Revive your friend with a Tarot Card.
Correctly identify the ghost 3 times.
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