Old blues players say they play the blues to chase the blues away. Stephen King, master horror writer, has written that scaring is caring. It all comes down to facing fright to get the fright dealt with. You face the ghost or it stays with you and haunts you. That doesn't sound too good to me.
Reading a novel like The Unholy sets religious horror smack dab in front of us. We can't run from it unless we stop reading. If you read The Unholy it may affect dreams, bring bad religious experiences back to consciousness. Horrid stuff stays locked away in the basement of our minds unless it's brought out into the light of day, consciousness. It grows rancid there, psychically smelly, grotesque.
I watched The Conjuring last night, a really decent horror flick. Terrible things happen in families and are pushed away. People try to force forgetfulness. Ha! It's locked in the basement. And, it knocks, bangs, on the door and gets out. Way, way scary. An exorcism is needed. Finally...you let it out then call it by name and cast it out and back into the miserable realms that birthed it.
We finished the movie, slowed our hearts from racing, sighed, and said "Good movie." We felt relief. It let loose hidden tensions and in ways not immediately discernible cleared out our heads. It was a good story. Horror heals, blows out clogged psychic tubes, chases horror away, and ultimately unleashed, as in The Unholy, insights, changed perspectives, and intense emotions stored in the basement of our minds.