The phenomenon of mass conversion in Spain (1391) and the creation of new communities of forced converts (anusim) created an urgent need for the consolidation and reinforcement of the communities’ Jewish identity. A complex language of conversion had to be developed in order to create an updated lexicon responding to the unprecedented demands of the new socio-religious discourse. The not-yet-mature identities of the new groups of conversos inspired the new Hebrew language of conversion. At the same time, this new language was actually an ideological attempt to shape new religious boundaries. One of the main characteristics was the development of literary forms to distinguish the good, still-Jewish anusim from the bad conversos. Professional Jewish scribes valued the Hebrew Bible above all and, using its expressions and allegories, developed a code that could be fully deciphered by scholars from the same intellectual milieu. Reading these verbal codes today demands careful evaluation and meticulous comparison between the biblical context and the circumstances in the Spanish kingdoms in the aftermath of 1391.