Europe is suffering from a spiritual identity crisis. Some countries rejected the historical preambulum to a European Constitution because Christianity was mentioned as one of the founding elements of the union… At the heart of the crisis is the loss of the spiritual basis on which the Continent had been united, mostly the idea of a Christian civilization. This address investigates the growth of this idea through the centuries as well as the causes of its recent decline and, in some areas, even loss. Can a European union survive without its founding idea? Are other models available, such as for instance that of a United States of Europe, on a purely economic basis? What is the difference between Europe and the USA in this respect? Louis Dupré is the T. Lawrason Riggs Professor Emeritus in Yale University’s religious studies department.