What is the main conflict in The Mark: The Beast Rules the World by Tim LaHaye?

The Mark: The Beast Rules the World is the story of Nicolae Carpathia's attempt to rule the entire planet and the resistance led by a few who believe in Christ. The book begins with a speech by Carpathia, pledging that he will not tolerate those who have called him the Antichrist. David Hassid is one of the Christians, and the first chapter begins with David searching for his fiancée, Annie. He will later discover that Annie was killed by lightening called down from the sky by Carpathia's false prophet, Leon Fortunato. David works in the corporation that governs the entire planet, the Global Community. Carpathia runs the organization and has not yet discovered that there are a few within the organization who are Christians.