...the loss within fifty years of the most fertile regions of the empire, the repeated defeats of imperial armies, and the devastation and growing poverty of what remained was a profound shock to the Byzantine world. Why should God have allowed Arabs so to humiliate the Chosen People of the Christian empire? The only answer within their system of beliefs that offered any reassurance for the future was the familiar one of God’s punishment of sin, which in turn, given the scale of the disaster which had overwhelmed the empire, implied the need for a fundamental reassessment of their relations with God if he were to restore them to his favor. Much of the history of the Byzantine world from the seventh to the ninth century can be seen as a series of attempts to make the empire pleasing to God…

—Mark Whittow, The Making of Byzantium: 600-1025 (1996), pp. 136.

The characters in Lest Darkness Fall are not modern people placed into a medieval world while retaining modern motivations. No, they will experience the fears of premodern times: the fear of the unknown, of strange monsters, of evil working unseen to subvert the good, of the horrible powers wielded by mages, of everything they cannot explain because they have not the mental tools or experiences of the modern world.

Can the players divest themselves of modern thought, and accept a world where there are other explanations for natural processes, explanations that make the world very strange and our place in it very precarious? The answer will turn on the religion, which must be central to the story and supply the means by which the characters cope with the world. In the world of the Eastern Empire, religion is the driving force for adventure.

Faith in the True God once spread to the four corners of the world. Then the Dark Lord arrived, and harried the faithful across the land. Now, only the diminished Eastern Empire openly resists the Dark Lord. Why has the True God allowed this? The faithful admit but one answer: punishment for sins. The people of the Eastern Empire must redeem themselves in the eyes of the True God. The characters will be instruments of this redemption.