Eastern Christianity is pluralistic. How might exchanges among Christians in geographic areas where different expressions of Christianity developed in the ancient Near and Middle East have been determining factors in the evolution of specific Churches? Encounters among Christians during Late Antiquity and the Middle Ages resulted in fertile adaptations and enrichments leading, through mutations and cross-influences, to the emergence of new identities. Such interculturality provides a response to the challenges of the dominating Byzantine, Persian, and Arabic cultures, as expressed through intellectual currents, artistic influences, and constructions of traditions. The selected articles presented here, several updated by their authors, have marked the field of Eastern Christian studies in recent decades. The comparative approach enables the reader to better grasp the exceptional impact of the cultural contacts among Christians in the East. This volume aims to be a useful tool by offering a synthesis of the research investigations and methodological approaches on Eastern Christianity as a crossroads of cultures.