Riding the surge in Christian-themed books, LaHaye signed a deal with Bantam Books to publish a new four-part Armageddon thriller. LaHaye is co-author of the doomsday series Left Behind, which sold 50 million copies. No surprise here. The religious books market hit $2.4 billion in 2001 and is projected to grow 3.7% annually through 2006. HarperCollins and Doubleday now have Christian book divisions.