The chapter takes stock of the major trends in recent scholarship of medieval heresy and ecclesiastical repression, identifies promising research avenues, and provides an overview of the way in which the papacy confronted the perceived menace of heresy in the central Middle Ages, considering the representations of and responses to religious dissent displayed by the official Church alongside its own motifs and transformations. The implementation of anti-heresy measures are thus observed in light of the main historical developments of the papacy in the central centuries of the Middle Ages: the eleventh-century reform and its institutional legacy; the zenith of papal monarchy; and the Avignon papacy and its political and intellectual developments. In all these different contexts, variously permeated by the ideal of papal theocracy, the Holy See fashioned apt legal and theological responses intended to contain what was featured as an enduring peril threatening the Church and Christendom.

Only rarely do medieval anti-heresy writings contain discussions about Christian communities in the East. Greeks, Armenians, Jacobites, Georgians or Nubians are usually absent from Western anti-heresy treatises, even when these are concerned with the Oriental sects from late antiquity drawn from Augustine and their subsequent updates. Indeed, the pragmatic concern to defeat those sects which seemed to be threats to the Latin West was the obvious mission inspiring the authors of most anti-heretical polemic.

Yet we do have a few treatises, directed against a great variety of errors, which also contain refutations of the errors of various Eastern Christian groups. The mid-thirteenth century Tractatus fidei contra diversos errores (Treatise of faith against various errors) by Benedict of Alignan, for example, engages with the errors of Greeks and Armenians, while also including discussions of Muslim beliefs and Jewish practices. Similarly, various anti-heresy treatises compiled in the fourteenth century include lists of errors of the Eastern Christians: they comprise Guido Terreni's Summa de haeresibus et earum confutationibus (Summa of Heresies and their Refutations), Alvarus Pelagius's Collyrium fidei contra haereses (Eye-salve of Faith against Heresies) and the renowned Directorium inquisitorum (Directive for Inquisitors) by the Dominican inquisitor Nicholas Eymerich. The two latter works include rebuttals of the Greeks only, whereas Guido's Summa contains lengthy descriptions and refutations of the errors of Greeks, Armenians, Georgians and Jacobites, with a special focus on the Greeks and Armenians. In addition, Guido engages in polemical argumentation against the doctrines and practices of the Jews, while one copy of the Summa contains a further fragment referring to twenty-five errores Sarracenorum, whose attribution to the same author has however been disputed.

How did Eastern Christians’ errors fit into anti-heresy treatises? And what do discussions about these groups reveal about learned approaches to heresy in the later Middle Ages? This essay focuses on what Guido Terreni and Alvarus Pelagius had to say against heresy in two comprehensive summae that were produced in the intellectual milieu of the Avignon court. I shall consider these treatises and look comparatively at the treatises by Benedict of Alignan and Nicholas Eymerich, in order to examine the place occupied by Eastern Christianity in the construction of a universal knowledge of heresy in the later Middle Ages.

On 13 December 1334, a few days after the death of John XXII (1316–1334), twenty-four cardinals gathered in conclave in Avignon. By the end of the week, the majority – according to some, all – of the assembly elected as John's successor the Cistercian cardinal Jacques Fournier (c.1285–1342). Born in Saverdun in the Ariège region, he ascended the papal throne on 8 January 1335 with the name of Benedict XII, and died in Avignon. According to the Florentine chronicler Giovanni Villani, the election was arduous and Fournier's name was proposed ‘almost as a dare, believing that it would not be done’ (quasi per gara, non credendo venisse fatto). The choice of one ‘regarded as the lowest of the Cardinals’ (il più minimo de’ cardinali) thus astonished many, probably on account of the new pontiff's political inexperience. Villani further remarks: ‘And once he was elected pope, everyone was surprised, and he himself, who was present, said: “You have elected an ignoramus” (Avete eletto uno asino)’.

Regardless of Villani's report, Jacques Fournier's pontifical election does not appear as something completely unexpected when considering his former career, as well as the influence of his maternal uncle Arnaud Novel – doctor of law, Cistercian abbot of Fontfroide, cardinal, and candidate to the papal throne after the death of Clement V.

During the fourteenth century various religious, political, and military factors came into play that would shape the major lines of intervention of the Apostolic See in the Near and Far East. In the first instance, the issue of the separation between the Latin and Eastern Churches remained unresolved after the substantial failure of the Second Council of Lyon (1274). Not only were the Oriental Churches a long way from accepting the primacy of the pope, but the Il-Khanid conversion to Islam had further thwarted any aspiration to widen the frontiers of Latin Christendom. And while the Armenians had formally accepted submission to the Roman Church, the Avignon popes continued to suspect, and investigate, unorthodoxy in Armenian doctrine and religious practices. The second fundamental factor affecting papal Eastern policies in the fourteenth century was the rising power of the Mamluk sultanate and the Anatolian Turkish principalities. Their military expansion in the Eastern Mediterranean region was the reason for the frequent appeals of Christian rulers for the assistance and support of the Holy See. Moreover, the gravity of the Turkish invasions in the Levant was in part responsible for directing the crusading activity towards Romania, delaying the magnum passagium against the Mamluks in the Holy Land.

However, the activities of the Holy See in the partes Orientis were not only conditioned by exogenous factors. Warfare between various Western sovereigns, as well as the economic situation of European bankers, affected the pope's capacity for intervention in the East in a significant way, preventing the realization of the crusading project. As Benedict XII openly remarked, the passagium transmarinum could not take place without first restoring peace among the Christian rulers.