The contemporary societies of the West are characterized by a collision of radically incommensurable cultures, that of traditional Christianity and that of the robustly laicist cultures that took shape in the nineteenth and twentieth centuries, drawing not only on the French Revolution and the Western European Enlightenment but also on deep roots in the synthesis of faith and reason that framed the thirteenth-century Western Christian Middle ages. This article explores the foundational contrast and conflict between traditional Christian bioethics and the (...) now-dominant secular culture through a portrayal of the historical and conceptual geography of the collapse of the Christendom established by St. Constantine the Great, Equal-to-the-Apostles, and on account of the emergence of secular fundamentalist states. The question is addressed anew as to what Athens can have to do with Jerusalem, as well as to what the Academy can have to do with the Church. The differences between a traditional Christian bioethics and a secular bioethics are illustrated in terms of questions bearing on the use of life-prolonging and death-postponing treatment. (shrink)