In early eighteenth-century Prague, Jesuit Franciscus Haselbauer (1677–1756) attempted to convert Jews through missionary catechetical manuals in German and Yiddish. His Brief Catechism from 1730, a condensed version of earlier works, provided essential Catholic doctrine in a form adapted for quick and easy instruction. This study situates the catechism within the socio-political landscape of Habsburg recatholization and anti-Jewish measures, exploring its role as both a religious guide and a tool for integration. Haselbauer’s linguistic strategies—translating Catholic concepts into Jewish religiolect while introducing Catholic terminology—facilitated the transition from Jewish to Christian identity. His bilingual approach also addressed linguistic adaptation, with Yiddish easing initial comprehension and German fostering social inclusion. Ultimately, the Brief Catechism functioned as a temporary bridge to Catholicism, reinforcing conversion’s transformative and irreversible nature.