In Spain, in 1501 the conversion of Muslims to Christianity was thought possible, hence the decreed baptisms; by the end of the century metanoia was deemed impossible. Similarly, religious otherness was thought to be surmountable; yet, it ultimately became indelible or racialized. These construction processes helped to discursively justify the expulsions of Christians, baptized descendants of Muslims, in the years 1609-1614. The importance of language in these justifications was arrived at through the study of referential language in texts, and a trans-Atlantic comparative approach. The discursive (re)construction and (re)inscription of otherness were traced through a variety of sixteenth-century ecclesial texts. Before these communities came to be named the so-called “moriscos” there were important changes in meaning and usage of other phrases and terms, such as “new Christian” and “newly converted.” The referential language was still in transition throughout the century and the processes are easily hidden by the historiographical premature and (over)use of the term “morisco.” Moreover, the full transition toward the racialized term “morisco” occurred closer to the eighteenth century and mostly across the Atlantic. The justifications rely on these communities being non-Christian and non-Spanish: suspect and alien. “Morisco” is not often a good metonymy. The fact that “moriscos” discursively came to be considered non-Spanish and non-Christian did not mean that there was actual discernible or insurmountable otherness. Therefore, a level of difference in the peninsula was posited through the study of referential language related to Amerindians before and after baptism: especially given that Amerindians remained “indios” after baptism—an indication that difference could be overcome in the peninsula. Furthermore, an analysis of the Sistema de Castas where “morisco” was used revealed that the proliferation of categories on both sides of the Atlantic was to prevent these communities from ever reaching the status of old Christian or Spanish.