Here is the official book description:
A hotel explodes in Mexico City, and all available evidence points to an American citizen, Alex Valdez, as the terrorist. The FBI is desperate to find the truth before the Mexican government can. Dead Religion follows the trail of FBI agent James Allison, who leaves his family and journeys to Mexico in order to find what secrets lay behind the destroyed hotel and all the lives lost with it. To do that though, Alex Valdez’s life must be laid bare—the blood rite his parents left him and the ‘God’ they felt had been unleashed on the world. Agent Allison races to find the truth in Mexico City, to uncover Valdez’s life, before he finds himself face to face with the same terror.
That description does not do the book justice. The premise of the book is that an extra-temporal being, known as the Aztec god Huitzilopochtli, wants to get back in business. To do that he needs willing blood sacrifices. Channeling through Alex Valdez, Huitzilopochtli attacks through induced hallucinations and those hallucinations begin to infect anyone who comes in contact with Valdez. Often the characters in the book, and sometimes the reader, can’t tell reality from hallucination. Valdez fights the hallucinations and Huitzilopochtli. Valdez must kill Huitzilopochtli to end the madness. Huitzilopochtli, to gain former power, must cause Valdez to willingly sacrifice himself to the god. Who will win?
If you are a fan of Stephen King stories you will like this book.