The 13th Demon: Altar of the Spiral Eye — Bruce Hennigan

When Jonathan Steel wakes up on a beach in a raging thunderstorm, naked, beaten, and bleeding, he has no idea who he is or how he got there. But just as he starts to make progress in his slow journey to recovery, tragedy strikes again, taking everything in his new life that he has come to love and rely on.
Filled with rage and a thirst for revenge, he searches the countryside for the entity responsible -- an entity called only the Thirteenth Demon. His quest brings him to Lakeside, Louisiana, and a small country church where evil is in control and strange writing on the walls, blood-soaked floors, and red-eyed spiders have appeared in the sanctuary.

As he faces the final confrontation with an evil presence that has pursued him all of his life, he must choose between helping the people he loves or destroying the thirteenth demon.