What is the main conflict in The Reason for God: Belief in an Age of Skepticism by Timothy Keller?

"The Reason for God, Belief in an Age of Skepticism," by Timothy Keller, is a pro-Christian work which lays out the major criticisms that modern skeptics have about faith and in particular Christianity. The author takes on each criticism and provides the relevant Christian response. The criticisms include the belief that there can't be just one true religion. He points out that historically, many of the major religions teach the one-religion philosophy and provides arguments that make the case that Christianity is that one true religion. He includes the many efforts by man to repress and eradicate religion and how these efforts have historically resulted in stronger belief.