The volume traces more than two millennia of the history of Christianity and of the Churches, marking the vast time span in the ancient, medieval, modern and contemporary ages and dwelling on some fundamental points: from the preaching of Jesus of Nazareth to the statute of religio licita at the time of Constantine; from the foundation of a Christian Europe to the globalization of Catholicism; passing through real and proper fractures, such as the Eastern Schism (1054), Luther's Reformation and the consequent genesis of the plurality of Confessions, the French Revolution, secularization, totalitarianisms and the Second Vatican Council. Moments of transition and change that lead the reader to question the future, the Christianity of the third millennium, grappling with the new international arrangements and with the spread of religious fundamentalism.The text is completed by geographic maps and fourteen representative profiles of the historical evolution of a religion that has hitherto been a majority.