I will be presenting some of my early research findings from my dissertation and looking to discuss their implications. My dissertation centers on fifteenth- and sixteenth-century reception of a single anti-Islamic polemic written at the turn of the fourteenth century by Riccoldo da Montecroce, a Dominican friar from Florence. The polemic, called Liber contra legem Sarracenorum has been preserved in twenty-nine extant manuscripts from the fourteenth, fifteenth, and sixteenth centuries. Additionally, the work was translated into Greek, Spanish, and German and printed on several different occasions. It was not only fellow Dominicans or even fellow Catholics who disseminated Riccoldo's work. Martin Luther himself translated the German edition and had it published in the context of continued threats from the Ottoman Empire. Nor did the reception of this work end in the early modern period. As recently as 2002 and in as close a place as Missouri, an English translation of the work was published by ‘Lutheran News,’ following the attacks of 9/11. In my dissertation, I am hoping to look at this reception in order to understand why this work proved so useful to readers. What was it about this particular polemic that lent it to a wide readership? How was it being adapted in this new period of relations between Western Christians and Islam? More broadly, I am interested in analyzing the role of religious justifications in a period that has been characterized by many historians as an age of secularization. In this presentation, I will detail some of the ways that Riccoldo's work became influential in the early modern period, bringing his polemic to intersect with topics such as humanism, conciliarism, the fall of Constantinople, and the Reformation.