The Bride Collector by Ted Dekker

In this psychological thriller, an FBI agent with a troubled past is on the hunt for a serial killer who believes he is on a divine mission to collect brides for God, leaving his victims posed as if in a serene marital bliss after their deaths. The killer's twisted theology and the agent's own personal demons intertwine as the investigation leads to a group of mentally ill patients who may hold the key to stopping the murderer. As the body count rises, the race against time intensifies, pushing the boundaries of sanity and redemption in a chilling game of cat and mouse. The 12174th greatest book of all time