The aim of this article is to retrace the figure of Jesus that was hidden under the polemical and apologetic strategy of the text known under the title Sefer Ḥizzuq Emunah (Strengthening of the Faith), composed at the end of the sixteenth century by Lithuanian Karaite scholar Isaac ben Abraham Troki (c. 1533–1594). Despite his belonging to a Karaite group, Isaac ben Abraham uses very often rabbinic quotations and Jewish classical commentators and this material was therefore perfectly intelligible to wider Jewish community, becoming also much more accessible to non-Jews and Marranos. Indeed, this text was translated in Spanish, Dutch, French, Portuguese and Latin before the XVII century. The Sefer Ḥizzuq Emunah was a privileged example of what the Christians knew about Jewish anti-Christian literature and was read by important European intellectuals and philosophers. This text circulated widely among European thinkers, becoming an important source of anti-Christian ideas among non-Jewish intellectuals. The influence of the Sefer Ḥizzuq Emunah demonstrates how closely the Jewish and Christian worlds interact and connect during early modern period.