The term heresy derives from the Greek hairesis. In classical Greek this word has a variety of meanings, all based on the verb haireo: "seizure" (of a city), "choice," "election," and "decision or purposive effort." This last meaning is the starting point for the Hellenistic and Christian use of the term to mean "doctrine," "school," or "received opinion," emphasizing the idea of a free decision or free choice of a doctrine or doctrinal authority. The word thus becomes a technical term for a philosophical school, a party, or a religious doctrinal system and its adherents. The term is applied to Stoics, Pythagoreans, Sadducees, Essenes, Pharisees, and Christians (see Acts 5:17, 24:5, 24:14, 26:5, 28:22). Neither in Greek nor in Hellenistic Jewish usage does the word have a negative, derogatory sense; it is an entirely value-free designation.
This situation changes with dramatic suddenness, however, with the rise of Christian literature. The New Testament already uses hairesis in a negative sense (see 1 Cor. 11:19, Gal. 5:20, 2 Pt. 2:1); the word therefore conveys suspicion, according to Heinrich Schlier. The semantic development in the direction of "sect, division, erroneous teaching" that is thus initiated continues in the early church; hairesis becomes a technical term for "heresy" and is applied primarily to the gnostics but also to Greek and Jewish "sects." (The older meaning of "doctrinal opinion, received view" is inflected, not completely but in large measure, in the direction of "erroneous teaching, false belief.") As Schlier says, "Hence the concept does not owe its meaning to the development of an orthodoxy. The basis of the Christian concept of hairesis is to be found in the new situation created by the introduction of the christian ekklesia. Ekklesia and hairesis are material opposites" (Schlier, 1964, vol. 1, pp. 182–183).
Despite this, the concept of heresy acquired sharp definition only gradually from the second century on; its distinction from the concept of schism took even longer. Furthermore, the process here described was not entirely comparable to the development in Judaism, although there was a strict temporal parallelism: From the end of the first century hairesis and the corresponding Hebrew word min were used in the derogatory sense of "heresy" and were applied to Christians and Gnostics, among others. One presupposition of this development was the emergence of rabbinical orthodoxy after Jamnia (c. 100).
This brief history of the term, the details of which are fascinating but cannot be presented here, shows in archetypal fashion the characteristic elements in the Christian understanding of heresy. This understanding was already present in the New Testament and did not have to wait for the coming of the later orthodox great church, although because of the "apostolic" authority the church had acquired in regard to doctrine, scripture, and episcopal office, the distinction between heresy and orthodoxy came to be more clearly drawn as the church developed, thus allowing the opposition to emerge with full clarity.
Theories of Heresy
The science of religions borrowed the term heresy from Christian usage as fixed in canon law and, as a result, has been very much influenced by the history of the Christian church. The traditional view of "orthodoxy" and "heresy" as equivalent to "true" and "false" was first challenged by Martin Luther in his disputation with Johannes Eck at Leipzig (1517), where he let himself be drawn into saying that even councils (of the church) can err, as they did in the case of Jan Hus. Luther and his disciples, though themselves branded as heretics by Rome, did not further develop this aspect of their critical revision of church history. As a result, the opposition of orthodoxy and heresy reappeared within Protestantism itself (the terminology used by the early church in dealing with heretics served as justification). Only after the appalling experience of the seventeenth-century religious wars were minds ready for another view of the matter.
In his Unparteiische Kirchen- und Ketzerhistorie von Anfang des Neuen Testaments bis 1688 (Impartial History of the Church and Heresy from the Beginning of the New Testament to 1688, published in 1699), Gottfried Arnold (1666–1714), a German Pietist theologian, attempted to show that Christian truth is to be found among heretics, schismatics, and sectarians (mystics), and not in the great church itself or in orthodoxy. Although Arnold simply offered a kind of inverted church history in which heresy, especially the views of the mystics, and not orthodoxy was given the seal of approval (by "impartial" Arnold meant "nonconfessional"), his book exercised an important and mellowing influence and blazed a trail for the ensuing period. Among his successors were J. L. von Mosheim (Ketzergeschichte, 1746–1748), C. W. F. Walch (Historie der Ketzereien, 1762–1785), F. C. Baur (Die christliche Gnosis, 1835; Lehrbuch der christlichen Dogmengeschichte, 1847, 1858; Das Christentum und die christliche Kirche der ersten drei Jahrhunderte, 1853, 1963), Adolf von Harnack (Lehrbuch der Dogmengeschichte, 1886, 1909), and Adolf Hilgenfeld (Die Ketzergeschichte des Urchristentums, 1884).
Toward the end of the nineteenth century, the work of the Religionsgeschichtliche Schule paved the way for a still more penetrating historical view of heresy and orthodoxy, not only because early Christianity came to be understood and interpreted in the context of its environment, but also because the barrier raised by the canon (considered to be the New Testament) was dismantled, and the New Testament was increasingly recognized as presenting only some of the many theological concepts and ideas of early Christianity. It became increasingly difficult to make a distinction between heresy and orthodoxy. The multiplicity of competing statements of faith regarding the "saving event" in Jesus Christ and its theological explanation showed ever more clearly that at the beginning of the church's history neither heresy nor orthodoxy was sharply defined or patent; both were concepts developed later.
This view of the matter has been presented most notably by Walter Bauer in his well-known book Rechtgläubigkeit und Ketzerei im ältesten Christentum (1934; Orthodoxy and Heresy in Earliest Christianity, Eng. trans. of 2d ed., 1971). A critical study of the early sources for the history of Christianity in Egypt, Syria, Asia Minor, and Greece shows that in these ancient Christian centers the Gnosticism later judged to be heresy was evidently regarded as Christianity. An orthodoxy came into being as the result of a lengthy historical and theological process. From a confrontation with other doctrines and practices something emerged that was to be regarded as the orthodox doctrine and practice: a canon, an episcopal office that drew its legitimacy from succession to the apostles (who were subsequently promoted to be the founders of the principal episcopal sees), baptism, imposition of hands, and eucharist.
Morphology of Heresy
This understanding of the origin of heresy and orthodoxy derived from the history of the Christian church is to a great extent valid for the history of religions. Bauer's thesis is therefore important also for the general study of religions. To that extent the unreflective, traditional concept of heresy is no longer applicable today; it must yield its place to the historical insight that heresy and orthodoxy are relative terms for religio-historical processes of quite different kinds. In any case the history of religions has no room for a theological and dogmatic judgment of these processes. It uses the concepts as purely historical categories or, better, as umbrella terms that make it possible to manage, in some degree, the multiplicity of contents presented by the history of religions. The history of religions cannot indeed bring about a revision of historical writing that would discard concepts that bear the mark of history. It can, however, exert a very healthy influence on the discussion of this subject by giving a critical presentation of historical events and causes that have led to oppositions between heresy and orthodoxy, which, in turn, have so often had tragic consequences. From the standpoint of comparative religion, an understanding of the applicability of the concept of heresy can shed light on the concept itself.
Religions in which heresy does not appear
Strictly speaking, it is possible to speak of "heresy," "schism," or "sect" only in connection with a certain type of religion, namely, religions founded by an individual or, as this author prefers to call them, "confessional religions." For in all the ancient popular religions that were not explicitly traced back to a founder or that did not have their own canonical document containing a revelation (as, for example, do Zoroastrianism and Judaism) there was no such thing as a "schism" or a "heresy" in a strict and specifically religious sense. This is to be accounted for by the fact that in these religions the particular religion or cult of the gods was coextensive with the people as a whole, that is, religion and national community were inseparable. An "apostasy" from the official cult binding on all meant a withdrawal from the nation; in other words, apostasy brought exclusion from the civic community (for the Germanic community this meant "outlawry"). Furthermore, the idea of a binding confession in the sense of a kind of rule or norm of faith was wholly alien to such a national or popular religion. As a result, divergent views on, for example, the nature of the gods or similar subjects did not immediately lead to a break with tradition and thus to divisions. Popular religions were therefore essentially tolerant and as long as there was no attack on the central cultic life showed themselves liberal toward the cults of other gods.
For illustration of this spirit one need only recall the interpretation of foreign gods, a tested means of adapting and of establishing equivalences. Communities or associations were of course to be found within popular religions, but they were for the most part simply specific manifestations of religio-social life, as, for example, the mysteries based on the ancient cults of the gods. There was no place for "orthodoxy" and "heresy" in the mysteries; indeed, a person could become an initiate in several mysteries. Nor do the groups and associations found in the religions of illiterate tribes form an exception to this rule. When there are no fixed norms set down in the doctrine of an exclusive community there is no room for "heresy."
In this world of national and tribal religions there was, however, an area that served as a very sensitive touchstone of orthodoxy in a broad sense of the term: the area of cult or worship. Here there was indeed the basis for a parting of the ways. It can be said that in a national or popular religion heresies and schisms in the narrow sense did not arise, because the necessary presupposition was lacking, but that on the other hand an individual could bring about a reordering, restructuring, or reformation, which then led to the founding of an entirely new religion or to a new cult. The occasion for such an innovation was almost always a radical critique of the traditional cult and of the sacred tradition closely connected with it. Zarathushtra (Zoroaster), the Buddha, and Muḥammad are the outstanding examples of this phenomenon. In the case of the Buddha, it is true, his community was initially only one philosophico-ascetical group among others. Also to be mentioned here is the pharaoh Akhenaton (Amunhotep IV), who failed in his attempt to introduce monolatry into Egypt.
There was still another area in national or popular religions in which divisions and formations of schools could arise: the area of philosophy, in Greece or ancient India, for example. The formation of new philosophical schools represented an "apostasy," or deviation from a doctrine; in fact, the Greco-Christian concepts of "heresy," "schism," and "sect" were derived precisely from this area of ancient cultural life. The concepts belong primarily to the philosophical and not the religious tradition. It is remarkable how ingenious Hinduism has been in reincorporating the "heresies" that spring from attitudes toward the Vedas. Hinduism is a popular religion (it may be said to be the only Indo-European one still in existence) that has a religious authority, namely the Vedas, as its guiding principle. As a result, a distinction is made between "orthodox" heretics and radical negators such as the Jains, Buddhists, and Sikhs. It is clear from this that the formation of heresies or schisms is connected with an authoritative revelation, whether this takes the form of a canonical document or a person.
Religions that give rise to heresy
Turning to religions that have a founder, one finds a radically different situation. (These "confessional religions" are not, it should be noted, identical with "world religions," and it is better to avoid the unfortunate term revealed religions, because it has too many theological associations.) All of the religions in question—Judaism, Zoroastrianism, Buddhism, Christianity, Manichaeism, and Islam—lay claim in one way or other to a normative doctrine. This does not from the outset always take the form of a fixed confession of faith, but there is at least a definite conception of faith and doctrine or, better, a central nucleus of doctrine that is used to separate "true" from "false" and that has taken written form in a sacred canon (thus "religions of the Book"). Such doctrines are, for example, monotheism or Yahvistic henotheism in Israel; the ethical dualism of Zarathushtra; the Buddha's knowledge and practice that lead to deliverance; faith in Jesus of Nazareth as the Christ; the ontological and anticosmic dualism of Mani; the confession of Allāh and of Muḥammad as his messenger.
The historian of the "confessional religions" mentioned above is familiar also with their slow maturation from preliminary stages and their development of a central doctrinal core that then became a distinguishing orthodoxy or orthopraxis. Orthodoxy is not present from the beginning as a fixed quantity (Islam is no exception here, though it might seem such at first glance). It is always a secondary development, establishing itself in the confrontation of divergent interpretations of the founder's "original teaching." Walter Bauer's thesis regarding the slow development of Christian orthodoxy from a number of divergent but, in the beginning, equally acceptable trends in early Christianity is to a large extent valid for the history of religions in general. Orthodoxy is in every case an interpretation of the doctrine or message that the founder has left behind and that frequently shows a lack of internal harmony, to say nothing of the fact that it is usually transmitted only in oral form. On the one hand, it is this state of the founder's teaching that leads to a struggle among the groups that subsequently form within the religious community. Local and social differences also play a part. On the other hand, while the preaching of a founder is indeed open to numerous interpretations in matters of detail, the fact is that once the tradition originating with him has been fixed in writing, his teachings as a whole take on a particular shape and form. The result is a certain uniformity among all his followers in regard to the basic norms of doctrine, belief, and behavior.
How heresy develops
In those religions that give rise to the development of heresy, a number of stages mark the process. Even in the lifetime of a founder there may already be disagreements on matters of doctrine or behavior (e.g., between the Buddha and Devadatta on questions of asceticism). The many-sidedness and occasional lack of clarity in the founder's teachings lead, especially after his death, to the formation of groups in the original community (groups that initially had more or less equal standing). In the struggle among these groups, one group emerges—often as the result of a compromise—that interprets and transmits the founder's heritage in an "orthodox" way. As a result, a point is reached at which there can be heresies or the formation of sects in the strict sense of these terms. (It has been seen in the case of the Christian concept of heresy that the existence of a "church" plays a normative role even before the rise of an "orthodoxy.")
It is difficult at times to determine how one particular movement is able to establish itself as orthodox. In most cases this movement or school preserves the heritage of the founder in a balanced and fully satisfactory way. In some cases only a rough determination of orthodoxy is reached; the result is the continued existence of groups with equal standing (as in early Indian Buddhism and the later Buddhism of East Asia; also in earlier Zoroastrianism as opposed to the official Zoroastrianism of the Sasanids). Islam too may be mentioned in this context because there is no "church" with an attendant hierarchy. The consensus of scholars who act as representatives of the community of believers becomes a regulating agency (the same holds for Judaism). Ideally, however, it is for the caliph as head of the community (ummah) to suppress heretics (kāfirs) and innovators (mubtadiʿ).
A tense opposition between "orthodoxy" and "heresy," "church" and "sect," marks the entire history of the founded religions and is also one of their fruitful major themes. Using the history of the Christian church as an example, Ernst Troeltsch has very impressively described this process as one of conflict between the institutional principle and the principle of voluntarism, both of which are contained in the gospel.
Causes of the rise of heresy
In parallel fashion it is possible to distinguish the following causes that lead to some typical forms of heresy:
- 1. Dogmatico-theological questions
understood as problems of doctrinal tradition and their interpretation (personal factors may at times play a role here, e.g., the apostasy of disciples). This cause is admittedly seldom found in a pure form (as Troeltsch established in connection with Christianity), but it is a main factor in almost all confessional religions (think of Jewish Christianity or Marcionism). Doctrinal questions supply the ideological backbone of almost all heresies and sects (e.g., Mazdaism or the Islamic Shīʿah sects); every "heresy" seeks doctrinal justification as an expression of its immediate self-consciousness.
- 2. Questions of lifestyle
or, if the reader will, of ethics and morality (in any case, problems of practice). Frequently these are directly connected with the questions mentioned above or else are consequences of divergent doctrines. In most instances sects follow a "radical" line and thus tend to extremism (e.g., in questions of asceticism or discipline in religious orders, as in Buddhism and also in Christianity).
- 3. Questions of ritual and cultic observance
Once again, these are usually connected with doctrinal problems but rarely in "book religions" as distinguished from "cultic religions." Even Christianity, a book religion, has known such cases: The controversy over the date of Easter in the second century, for example.
- 4. Social problems
which are closely connected with moral and ethical problems. Socio-revolutionary movements come under this heading. Marxist analysis and more recent sociological analyses have shed a great deal of light on this area, showing that a good many heresies have been the expression of critical situations in society (e.g., medieval heretical movements in Christianity and Islam, or the recent "religions of imminent salvation" in nonliterate cultures). Following Troeltsch, English sociologist of religion Bryan R. Wilson has interpreted modern sectary movements within Christianity, especially in the Anglo-American world, as expressions specifically of social protest and has once again shown that periods of social unrest are privileged times for the rise of sects. Social tensions and pressures in a society that is sustained and given its impress by an "established church" lead to movements of religious protest directed against state and church as a single undivided power. In the Middle Ages such movements appeared as "critical" manifestations within feudalism and asserted themselves most clearly in "heretical" movements (Bogomils, Albigensians, Waldensians, and so on). The important part played by this sort of background should not, however, lead one to interpret every religious sect or heresy as a crypto-revolutionary movement. There is good reason to reject the old ahistorical underestimation of such causes, but one should not replace it with a one-sided overestimation of them.
- 5. Political causes
These are often closely connected with the social causes described above, because the politico-religious ambitions of a stratum or class usually also involve social interests that can lead to divisions within an established religion of the type being discussed here. In Islam, for example, the vast majority of Shīʿī and other sects or heresies are religio-political movements that have been sparked by concrete disputes concerning, for instance, the position of the community leader. Or, they are simply a consequence of the overall structure of Islam.
- 6. Cultural, anthropological (racial), and ethnic factors
that are evident in Islam, in the history of the Eastern Christian church, and, to some extent, in Buddhism, for example, are factors that do not, of course, operate in isolation. Also to be mentioned under this heading is the continued influence of past forms of religion, the various forms of "paganism," for instance, which either give the impulse to emerging heresies and divisions or at least supply them with ideological material. Striking examples are Gnosticism, Manichaeism in the Iranian world, and the rise of the Nusayriyah and the Druze in the Islamic world.
- 7. The figure of a charismatic leader
often plays a role that should not be underestimated in the separate or combined operation of these various factors. The leader has an important part in shaping a heresy and its further course. The leader can develop from the founder of a sect into the founder of a new religion.
Gnosticism as Historical Example
One of the most striking examples of a heresy that had its own original worldview but on encountering another religion (Christianity) became part of its history, is Gnosticism, or Gnosis. By way of lay intellectuals it made its way into the Christian community as early as the time of Paul or, to put it differently, it attached itself to certain Christian ideas. The result was a development that turned a pre-Christian religious movement into a Christian heresy or, more exactly, a distinct movement or sect in the church. There can be no doubt of this in view of the different roles played in Gnostic systems by the spiritual man who founds a Gnostic sect and by Jesus Christ as authoritative bringer of revelation, and in view, too, of Gnosticism's very different soteriology. But before the point was reached at which Gnosticism became a heresy or sect, it was in many places the church itself, with its own scriptural tradition and exegesis. It is known from numerous Gnostic writings that the Gnostics regarded themselves as the real Christians and intended to be the true church. To Celsus, of course, the Gnostics were Christians. There were groups of Gnostics who formed tightly knit churches, as the letters of Paul, the Gospel of John, and the Nag Hammadi writings show in their different ways; even Irenaeus, a father of the church, admits this. Gnosticism was therefore not natively an anti-Christian or antiecclesial movement. Its entire exegesis of scripture disproves this interpretation. It was turned into such by the heresiologists, who, like Paul before them, initiated a process of elimination to which Gnosticism finally fell victim.
The reaction of Irenaeus provides a good mirror in which to study this development. He equates gnosis with paganism; in fact, he attacks the Gnostics as worse than the pagans. He sees them as imitators of the pagans and yet not as genuine pagani but rather heretics of the Christian age who disagree with the church on the real origin of things and on true Christian doctrine. Unlike Hegesippus and Hippolytus, Irenaeus knows nothing of an earlier prehistory of gnosticism and is familiar only with Simon Magus as founder and first heretic. To a great extent, Irenaeus's view of the matter determined the course followed by subsequent heresiologists: They knew Gnosticism only as a Christian heresy (a conception that only slowly yielded its place to another during the nineteenth and twentieth centuries).
It was in the confrontation with gnosticism (including Marcionism) that ecclesial orthodoxy took form. Scholars have always realized that this process of distinction and separation was of radical importance, but they have not always understood what the process meant for both sides. It is more than a simple coincidence that to a great extent both the church and the Gnostic "heretics" used the same arguments in their disputes, especially the arguments from tradition and from the unbroken line of witnesses. Both sides made use of the same proofs, as a study of Irenaeus and the texts of the Christian Gnostics shows; these proofs were those of apostolic authority, scriptural exegesis, and tradition. Tradition provided the Gnostics with an impregnable fortress: the secret tradition that is for practical purposes identical with liberating knowledge and that has been entrusted solely to spiritual persons or initiates, and is completely kept from the ignorant (see, for instance, the Gospel of Thomas). Recent studies have shown that on certain points of his terminology for the church, Irenaeus was dependent on the gnostics; for example, diadoche and paradosis, used in connection with the principle of succession, were already current terms among the gnostics. This is why Irenaeus was unable to get the better of the Gnostics with arguments of this kind, even though he repeatedly attempted to do so.
Irenaeus's principal weapon, however, was the concept of gnosis itself: "Irenaeus uses the concept of gnosis to distinguish between Church and heretics by focusing the entire dispute on the fundamental and always presupposed attitude of the human person to revelation and God" (Norbert Brox, Offenbarung, Gnosis und gnostischer Mythos bei Irenaeus von Lyon, Salzburg, 1966, p. 170). Another and quite different way of attaining true gnosis, a way essentially different from that of the Gnostics, is available to human beings: the way of humble knowledge of the order of salvation that is attested in scripture, handed on by the apostles, and described in the church's teaching and preaching and that is explained, of course, by Irenaeus himself. True (ecclesiastical) gnosis thus becomes a standard by which heretical gnosis is shown to be an erroneous figment of the imagination. This example makes clear the complicated way in which the distinction between heresy and orthodoxy was achieved and how the two could not become distinct without having first fertilized one another.
Similar processes are to be seen at work in other sectors of the history of religions. Islamic orthodoxy took over to a large extent the philosophical terminology, though classified as heretical, of the Muʿtazilah who had assimilated the Hellenistic heritage. Both Shīʿīs and Sunnīs developed their own sunnah or religio-legal tradition and claimed justification for it in Muḥammad (in the case of the Shīʿah, by way of ʿAlī, Fāṭimah, and their sons as the Prophet's spokesmen). In Zoroastrianism the problems of monotheism and dualism, which had their basis in the theology of Zarathushtra, led alternately to orthodoxy and heresy, a process in which the civil authorities played a part. Thus the religion of the god of time (Zurwān) was dominant in the later Arsacid and early Sasanid periods as the accepted interpretation of the Zoroastrian tradition. Later on, however, especially once the Zoroastrian religion had been outlawed, this form became a heresy to be bitterly opposed, and modern Parsis even reject as non-Zoroastrian a dualist interpretation of the message of Zarathushtra. Thus it is made repeatedly clear that the relation between heresy and orthodoxy is one of interplay that does not permit historians of religion to pass any clear value judgment on the matter; rather they see in this situation clear evidence of the dynamism and vitality of religion.
There is no complete treatment of heresy as a phenomenon in the study of religions. There are, however, countless works on heresy as found in the various traditions. The following list is a selection from these.
- Assmann, Jan. "Die 'Häresie' des Echnaton: Aspekte der Amarna Religion." Saeculum 23 (1972): 109–126.
- Baetke, Walter. "Der Begriff der Unheiligkeit im altnordischen Recht." In his Kleine Schriften, edited by Kurt Rudolph and Ernst Walter, pp. 90–128. Weimar, 1973.
- Brosch, Joseph. Das Wesen der Häresie. Bonn, 1936.
- Forkman, Göran. The Limits of the Religious Community. Lund, 1972.
- Leipoldt, Johannes, and Siegfried Morenz. Heilige Schriften. Leipzig, 1953.
- Morenz, Siegfried. "Entstehung und Wesen der Buchreligion." Theologische Literaturzeitung 75 (1950): 709–715.
- Nigg, Walter. Das Buch der Ketzer. Zurich, 1949.
- Rudolph, Kurt. "Wesen und Struktur der Sekte." Kairos, n. s. 21 (1979): 241–254.
- Schlier, Heinrich. "Hairesis." In Theological Dictionary of the New Testament, edited by Gerhard Kittel, vol. 1. Grand Rapids, Mich., 1964.
- Simon, Marcel. "From Greek Hairesis to Christian Heresy." In Early Christian Literature and the Classical Intellectual Tradition, in Honorem Robert M. Grant, edited by Wilhelm R. Schoedel and Robert L. Wilken, pp. 101–116. Paris, 1979.
- Wach, Joachim. Sociology of Religion. Chicago, 1944.
- Bauer, Walter. Orthodoxy and Heresy in Earliest Christianity. Edited by Robert A. Kraft and Gerhard Krodel. Philadelphia, 1971.
- Berkouts, Carl T., and Jeffrey Burton Russell. Medieval Heresies: A Bibliography, 1960–1979. Toronto, 1981.
- Betz, Hans Dieter. "Orthodoxy and Heresy in Primitive Christianity." Interpretation 19 (July 1965): 299–311.
- Betz, Hans Dieter. "Häresie: Neues Testament." In Theologische Realenzyklopädie, vol. 14, pp. 313–318. Berlin, 1984.
- Gensichen, Hans-Werner. Damnamus: Die Verwerfung der Irrlehre bei Luther und im Luthertum des 16. Jahrhunderts. Göttingen, 1955.
- Grundmann, Herbert. Ketzergeschichte des Mittelalters. Die Kirche in ihrer Geschichte, no. 3. Göttingen, 1963.
- Grundmann, Herbert. Bibliographie zur Ketzergeschichte des Mittelalters, 1900–1966. Rome, 1967.
- Harrington, Daniel J. "The Reception of Walter Bauer's Orthodoxy and Heresy in Earliest Christianity during the 1970s." Harvard Theological Review 73 (January–April 1980): 289–298.
- Leff, Gordon. Heresy in the Later Middle Ages. Manchester, 1967.
- Loos, Milan. Dualist Heresy in the Middle Ages. Prague, 1974.
- Rudolph, Kurt. "Gnosis: Weltreligion oder Sekte." Kairos, n. s. 21 (1979): 255–263.
- Troeltsch, Ernst. The Social Teaching of the Christian Churches. 2 vols. New York, 1931; Chicago, 1981.
- Turner, H. E. W. The Pattern of Christian Truth. London, 1954.
- Le Boulluec. La notion d'hérésie dans la littérature grecque IIe-IIIe siècles. Paris, 1985. Origins and development of the notion of heresy in the first Greek Church Fathers, from Justin to Origenes.
- Lüdemann, Gerd. Ketzer. Die andere Seite des frühen Christentums. Stuttgart, 1996. A vigorous novel appraisal of facts and problems by a leading albeit controversial German New Testament scholar. Extensive bibliography.
- Pourkier, Aline. L'hérésiologie chez Epiphane de Salamine. Paris, 1992.
- Simonetti, Manlio. Ortodossia ed eresia tra I e II secolo. Soveria Mannelli, Italy, 1994. A collection of influential essays by the foremost Italian specialist.
- Scarcia, Gianroberto. "L'eresia musulmana nella problematica storico-religiosa." Studi e materiali di storia delle religioni 33 (1962): 63–97.
- Scarcia Amoretti, Biancamaria. "Die historische Entwicklung der Sekten im Islam." In Der Islam, vol. 3, edited by Anne-marie Schimmel, pp. 100–156. Stuttgart, 1990. A typological and historical survey by a leading specialist.
- McEleney, Neil J. "Orthodoxy in Judaism of the First Christian Century." Journal for the Study of Judaism 4 (1973): 19–42.
- Scholem, Gershom. Major Trends in Jewish Mysticism. 3d ed., rev. New York, 1954.
- Halm, Heinz. Die islamische Gnosis. Zurich, 1982.
- Laoust, Henri. Les schismes dans l'Islam. Paris, 1965.
- Lewis, Bernard. "Some Observations on the Significance of Heresy in Islam." Studia Islamica 1 (1953): 43–63.
- Boyce, Mary. Zoroastrians: Their Religious Beliefs and Practices. London, 1979.
- Boyce, Mary. A History of Zoroastrianism, vol. 2, Under the Achaemenians. Leiden, 1982.
- Widengren, Geo. Die Religionen Irans. Stuttgart, 1965.
- Zaehner, Robert C. Zurvan: A Zoroastrian Dilemma. Oxford, 1955.
- Shaked, Shaul. Dualism in Transformation. Varieties of Religion in Sasanian Iran. London, 1994. A learned and vigorous examination of a very controversial issue. See the critical review by another prominent specialist: Mary Boyce, "On the Orthodoxy of Sasanian Zoroastrianism," Bulletin of the School of Oriental and African Studies 59 (1996): 11–28.
- O'Flaherty, Wendy Doniger. "The Origin of Heresy in Hindu Mythology." History of Religions 10 (May 1971): 271–333.
- Bareau, André. Les sectes bouddhiques du petit véhicle. Saigon, 1955.
- Dutt, Nalinaksha. Buddhist Sects in India. Calcutta, 1970.
- The Heretical Imperative, by Peter Berger, ISBN 9780385142861 ISBN 0385142862
Rudolph, Kurt. "Heresy: An Overview." Encyclopedia of Religion. Ed. Lindsay Jones. Vol. 6. 2nd ed. Detroit: Macmillan Reference USA, 2005. 3920-3925. Gale Virtual Reference Library. Gale.