Figure 2. Detail from the Decretals of Gregory IX with gloss of Bernard of Parma (“Smithfield Decretals”), ca. 1300–1340. London, British Library, Royal MS 10 E IV, fol. 164v. London, TNA, E401/1565 M1.

      Other sources depicted Jews as intent on turning Christians away from Christianity, even if not specifically to Judaism. Pictorial representations from Castile, German lands, France, and England of the widespread Marian miracle story known as the Theophilus legend—a tale in which a Jew facilitates a pact between the devil and a demoted archdeacon named Theophilus—portrayed this Jewish intermediary as physically pushing or pulling Theophilus toward the devil, who demanded that Theophilus “deny Christ and his mother” (Figure 2).¹⁰⁸ Accusations that reverberated across southern France in 1321 to the effect that lepers had poisoned wells also gave voice to the fear that Jews were intent on spiritually corrupting Christians. According to multiple French chronicles, Jews persuaded the lepers to poison wells, and first they made these lepers “renounce the Catholic faith.”¹⁰⁹

      During the later decades of the thirteenth century and the first decades of the fourteenth, Christian concerns about Christian apostasy and its alleged encouragement by Jews remained part and parcel of broader concerns about the instability of Christian identity. Alarm about apostasy to Islam and about Muslims as agents of Christian apostasy ran especially high in Mediterranean Europe. In the 1260s, in two crusade sermons, Cardinal Odo of Châteauroux accused Muslims in Lucera in southern Italy of “seizing many Christians, especially women and children, infecting them with the error of the law of Mohammad, and blinding them spiritually.”¹¹⁰ The collection of hymns known as the Cantigas de Santa María (Canticles of Holy Mary) of King Alfonso X of Castile depicted a Muslim woman in Tangiers as warning two female Christian prisoners that, unless they “became Muslims and renounced Christianity,” “she would put them both in chains and submit them to such great tortures that no sound piece of skin nor nerves nor veins would remain in their bodies; in addition, she would have them beheaded.” According to this text, one of the Christian women “said in fear that she would willingly [convert to Islam].”¹¹¹ In his novel Blanquerna (1283), the Catalonian polymath Ramon Llull (1232–1316) lamented that Christians living under Muslim rule had “no more belief in the Holy Catholic Faith, but renounce[d] it and t[ook] the faith of those among them they live[d] in opposition to the will of God.”¹¹² Compiled in the late thirteenth century by the Castilian Dominican Pedro Marín (1232–93), a collection of miracles allegedly performed by St. Dominic of Silos (1000–1073) prominently featured stories about the liberation of Christian captives who were on the brink of apostatizing to Islam at the hands of their Muslim captors.¹¹³ In 1290, Pope Nicholas IV appointed a new bishop of Morocco for the sake of, among other things, “reconciling [Christian] apostates” to the church.¹¹⁴ The 1321 well-poisoning accusations in southern France also reflected the fear that Muslims sought to turn Christians away from their faith. According to the deposition of the head of the leper colony in Pamiers, Guillaume Agasse, who appeared before Bishop Jacques Fournier (later Pope Benedict XII) and his deputies, Muslim rulers who allegedly supported the plot to poison Christians demanded that lepers “deny the faith of Christ and his Law” and that they spit and trample on “the cross of Christ and his body.” These Muslim rulers purportedly warned, moreover, that any lepers who refused to abjure Christianity would be decapitated.¹¹⁵ Attributed to the widely traveled Spanish theologian and bishop Pedro Pascual (d. 1299), a work known as the Biblia pequeña portrayed Jews as collaborating with Muslims in leading Christians astray. It contended that Jews visited imprisoned Christians in Muslim Granada and persuaded them to believe in “the false sect of the Muslims.”¹¹⁶

      Links between Christian anxieties about apostasy to Judaism, on the one hand, and falling into Christian heresy, on the other, are apparent in the subsuming, starting during the third quarter of the thirteenth century, of matters pertaining to apostasy to Judaism under the jurisdiction of the papal inquisition, which was established in the 1230s, as noted above, to eradicate Christian heresy. In 1267, in the bull Turbato corde, Pope Clement IV reported having heard, “with a troubled heart,” that Christians, “abandoning the truth of the Catholic faith, had damnably gone over to the Jewish rite.” Clement authorized and urged Dominican and Franciscan inquisitors to proceed against Christian apostates to Judaism. In addition, he instructed them to do so in the same way “as [they proceeded] against heretics.” The same personnel were now to monitor both arenas of Christian defection from the fold—falling into Christian heresy and apostasy to Judaism—using the same procedure. Clement also instructed inquisitors to impose “a fitting punishment” upon Jews found guilty of having “induced Christians of either sex to join [the Jews’] execrable rite.”¹¹⁷

      Several secular rulers explicitly recognized inquisitors’ jurisdiction over matters concerning apostasy to Judaism, and they sought to promote the inquisitorial prosecution of Christian apostates to Judaism and their Jewish abettors. In 1276, King Charles I of Sicily, Naples, and Albania—who was also Count of Provence, Forcalquier, Anjou, and Maine—ordered the seneschal and other officials of Provence to extend full support to the Dominican Bertrand de Rocca, whom