On the subject of detective thrillers and devil worshipping, I just finished Falling Angel, the book the movie Angel Heart is based on (recently reappeared on Kindle, hard to get hold of before). Very good. Everyone knows the twist, but the book doesn't rely on it, it's more a case of it approaching like a distant freight train, as it steadily builds towards the inevitable. Some nice prose to boot, he does a good Chandler turn of phrase.