Gosh, it's been so long since my last review...
Well to get started, I really like the feel of the piece. The organ has a nice classic tone to it, and the composition feels pretty convincing. I also really like the hollowness of the main theme here. The exorcism part at the end actually works pretty well too, and kinda reminds me of Alexander Andersson from Hellsing for some reason...
My only complaint is that those drums may seem a little too straight-forward. I like them a little more dynamic and acoustic-sounding, but just that's just my opinion. If you were aiming for a heavier beat to set the pace, I totally understand.
So all in all; great piece! It has a good (or should I say Evil?) spirit :D
If you're looking for more organ music, may I suggest that you check out my song "Terrorflame Trench". It has a pretty nice organ solo a little while out in the piece.