Responsa and law codes by the thirteenth-century Catalonian rabbis Moshe ben Nahman (Nahmanides) and Shelomo Ibn Adret make frequent reference to gentiles but hardly ever address Christians or Muslims as such. This silence about Christianity and Islam stems neither from ignorance nor self-censorship but rather from the ways in which these and other medieval European rabbis conceptualized the distinction between Jews and non-Jews. By emphasizing observance of biblical law as the most important characteristic of Judaism, Ibn Adret and his colleagues render detailed information about non-Jewish religions legally irrelevant while also offering a powerful polemical defense against Christian missionary efforts. The pervasive influence of theological and polemical notions about non-Jews on medieval halakhic literature complicates efforts to derive social historical data from these sources.