These pages represent the compendium of a long journey of more than twenty-five years. It would be simplistic to define this journey as exclusively intellectual, because it would be unthinkable without frequent visits to the Middle East, in particular to Turkey, the second Holy Land of Christianity, the ancient Asia Minor of biblical history, with its overwhelming Muslim population today. The fact is that, since many years now, the theme of hospitality has been the subject of numerous publications, studies, contributions and gatherings with protagonists of various opinions and expertise convening to give answers to questions related to the challenge of living together in the complex society of our contemporary world. It is precisely by letting ourselves be questioned by these complexities that we become aware that the challenge of hospitality is not merely economic or political but also spiritual. Claudio Monge addresses one of the key questions of today with an extremely ancient text from the deepest roots of our civilisation, Genesis 18, in which Abraham welcomes the three strangers who come to his tent and announce the conception of Isaac. Today, when millions are in movement, fleeing war and poverty, the question of how we are to receive strangers is urgent and inescapable. Monge explores this text through the traditions of three religions - Judaism, Christianity and Islam - which claim the assent of approximately half of the population of the world. Yet these three religions, all looking back in one way or another to Abraham, are often strangers to each other. If we could offer welcome to each other, what a powerful sign of hope this would be for our conflict torn world!