Over one billion Christians look to Rome, more than half of all Christians on the planet. But how did a small Jewish sect from the backwoods of 1st-century Palestine, which preached humility and the virtue of poverty, become the established religion of western Europe - wealthy, powerful and expecting unfailing obedience from the faithful? Amongst the surprising revelations, Professor MacCulloch tells how confession was invented by monks on a remote island off the coast of Ireland, and how the Crusades gave Britain the university system. Above all, it is a story of what can be achieved when you have friends in high places.