How did Christianity become the dominant religion in the West? In the early first century, a small group of peasants from the backwaters of the Roman Empire proclaimed that an executed enemy of the state was God's messiah. Less than four hundred years later it had become the official religion of Rome with some thirty million followers. It could so easily have been a forgotten sect of Judaism. Through meticulous research, Bart Ehrman, an expert on Christian history, texts and traditions, explores the way we think about one of the most important cultural transformations the world has ever seen, one that has shaped the art, music, literature, philosophy, ethics and economics of modern Western civilisation.