'Heresy and the Church' - a Summary of St Albans Cathedral's Course by Prof Tim Boatswain

1. Heresy and Early Christianity

Heresy is a concept that refers to a belief or opinion that profoundly and obstinately contradicts the established, official doctrines of a religious community, especially after having been formally condemned by that community's authority.

It is not simply being wrong but involves a conscious, persistent choice to deny a doctrine considered essential by the orthodox (correct) authorities of the faith. The term is primarily used within Christianity, though analogous concepts exist in Islam (bid'ah), Judaism (minuth), and other faiths. It represents doctrinal deviations. The focus of the term is on belief rather than practices, which are often labelled schisms. Whereas, Apostasy is when someone leaves a faith.

Therefore, the use of the term "heresy" is technically linked to a legitimate authority within the faith which can pronounce an individual a heretic and excommunicate them. In the Roman Catholic Church, the authority lies with the Pope; in the Orthodox Churches, it is embedded in Church Councils. Usually, an opportunity is given for recanting, but if an individual persists in a heretical belief, they are condemned, often resulting in their execution.

As the Christian Church developed, heresy emerged as clerics sought to define the religion’s core beliefs in the context of competing interpretations. Once Christianity became the state religion (CE c. 323) under Constantine the Great, imperial power was used to define a totalitarian Church orthodoxy. When the Roman Empire dissolved in the Western half, the Papal power maintained an absolutist approach, while in the East, Byzantine Emperors determined theological doctrines through Church Councils.

Heresy is doctrinal dissent that a religious authority has judged to be a fundamental betrayal of the faith's truth. Its definition is inseparable from power, identity, and an ongoing struggle to define orthodoxy.

2. Heresy and Orthodoxy 

In the first centuries of the Christian faith, before the creeds were crystallised and the canon closed, the Church was a battlefield of competing truths. It was an era of fervent exploration, where the message of Jesus collided with Greek philosophy, Jewish scripture, and Persian dualism. From this crucible emerged powerful alternative interpretations of the Christian faith and many movements later condemned as heresies, but whose challenges forced the early Church to define the very essence of its belief system.  Among the most influential in the Early Church were Marcionism, Montanism, Sabellianism, and the complex family of Gnostic movements, including Valentinianism. Their stories are a testament to the Church's pursuit of absolute truth, which resonated with the totalitarian state of the Roman Empire.

Marcionism 

In the mid-2nd century, a wealthy shipowner named Marcion proposed a radical solution to a troubling problem: how to reconcile the vengeful, warlike God of the Old Testament with the loving Father proclaimed by Jesus. His answer was breathtakingly simple: they were two different gods.

Marcion constructed a dualist theology. The creator of the material world, the God of the Jews, was a fearsome, but inferior, even malicious, demiurge. The true, previously unknown God of pure love and grace, revealed by Jesus, had come to save humanity. Consequently, Marcion utterly rejected the Old Testament and purged the emerging Christian writings of any Jewish influence. He produced the first known canon of scripture: an edited version of the Gospel of Luke and ten letters of Paul. He removed all references to the creator god.

Many clerics, with the political power of the emerging Church hierarchy, challenged his revolutionary ideology. To counter Marcion, the senior figures of Early Christianity began to define their own canon, affirming the Old Testament as sacred and broadening the accepted apostolic writings. Marcionism, therefore, is a primary reason the New Testament exists as it does: the heresy that forced orthodoxy to compile its book.

Montanism

While Marcion defined a version of the scripture, the Phrygian movement of Montanus, in the late 2nd century, challenged the Church’s growing institutional structure with a torrent of new revelations. Montanus and his prophetesses, Prisca and Maximilla, proclaimed that the age of the Paraclete (the Holy Spirit) had dawned in their own ecstatic utterances. They preached strict asceticism, forbidding remarriage and flight from persecution, and anticipated the imminent descent of the New Jerusalem in Phrygia.

Montanism was a heresy of charismatic volatility versus order. It posed a fundamental question: did the age of prophecy end with the apostles, or was the Spirit of Jesus revealing new truths? The mainstream Church, consolidating its episcopal authority and creeds, chose certainty and establishment. By rejecting Montanism, it decided that revelation had been completed in the apostolic annunciations, administered by bishops, not proclaimed by contemporary prophets. The clash between established order and exotic enthusiasm was drawn, a line that would re-emerge in movements from the Montanists to the Pentecostals.

Sabellianism

In the 3rd century, as the Church struggled to articulate the relationship between the Father, Son, and Holy Spirit, Sabellius offered a deceptively simple model: God is one person who manifests in three different sequential "modes" (Latin: personae, meaning "masks" or "roles"). Like an actor, the one God played the part of the Father in creation, the Son in redemption, and the Spirit in sanctification.

This "Modalist" heresy preserved God’s unity but at the cost of the distinct, simultaneous personal existence of the Trinity. It made the crucifixion a drama where God the Father suffered (Patripassianism), a concept that horrified theologians like Tertullian, who coined the term "Trinity" (Trinitas) to combat it. The defeat of Sabellianism was essential for the development of orthodox Trinitarian doctrine, which would later be codified at the Council of Nicaea: one God in three co-eternal, distinct persons or 'hypostasis'(substance).

Gnosticism & Valentinianism

Gnosticism (from gnosis, "knowledge") was not a single heresy but a diverse spectrum of movements sharing a core worldview: dualism. They held that the true, transcendent God is utterly alien to the flawed, evil material world, which was created by an ignorant or malevolent demiurge (often identified with the Old Testament God). Humanity, however, carries within a divine spark, trapped in the prison of the flesh. Salvation came not from faith or grace alone, but from receiving the secret knowledge of one’s true origin, the nature of the divine realm (Pleroma), and the passwords needed for the soul to escape the material cosmos after death. This knowledge was imparted by a descending redeemer figure, often Christ, who was purely spiritual and only seemed to have a physical body (Docetism =to seem).

Valentinianism,

Valentinus, a subtle theologian, founded this heresy in the 2nd century. It was the most sophisticated and influential Gnostic system. It created an elaborate mythos of divine emanations (Aeons), a detailed cosmology, and a nuanced anthropology dividing humanity into spiritual (pneumatic), soulish (psychic), and material (hylic) natures. Unlike some crude Gnostic sects, Valentinians often operated within mainstream churches, offering a deeper, esoteric interpretation of common scriptures and sacraments.

The Church Fathers, most notably Irenaeus (a Greek Bishop), in his monumental Against Heresies, waged total war on Gnosticism. They fought for the goodness of creation, the reality of Christ’s incarnation, and the public, universal nature of salvation. They countered the Gnostics’ elitist, secretive, and world-denying spirituality. In defining orthodoxy, they were, in large part, defining anti-Gnosticism.

These four heresies were not mere errors; they were live options, compelling alternatives that attracted devout followers. By confronting them, the early Church was compelled to address foundational questions: What constitutes the canon of Scripture? Is Revelation closed? Who is God—one, two, or three? Is the world God’s good creation or a prison?

In condemning Marcionism, Montanism, Sabellianism, and Gnosticism, the Church did not silence dissent so much as choose its own identity. It chose the God of Israel as Father of Jesus Christ, the authority of the bishop over the ecstatic prophet, the mystery of the Trinity over simple unity, and the sense of the Word made flesh over the secret wisdom of the spirit. The heretics, though defeated, were the indispensable sparring partners in the forging of Christian orthodoxy. Their ghosts still linger wherever these eternal tensions resurface between law and grace, spirit and institution, mystery and dogma.

3. Heresies and Orthodoxy

In the formative centuries following Christianity's legalisation (CE 313) by the Emperor Constantine, the Church faced fierce arguments for its intellectual and spiritual soul. This struggle was about the nature of God, salvation, grace, and the Church itself. The doctrines that emerged victorious were cemented in the Creeds, but the "lost" beliefs in heresies like Arianism, Donatism, Pelagianism, and Nestorianism were not just errors of understanding: they were compelling, logical alternatives that forced the Church to define, with complex and arcane judgements, the orthodoxy we know today.

Arianism

In the early 4th century, an Alexandrian priest named Arius posed the question: Is the Son truly equal to God the Father? His answer, derived from the tradition of Greek philosophical culture, based on rationality, was “no."

Arius taught that the Logos (the Word, Jesus Christ) was the first and greatest creation of God. "There was a time when the Son was not," he proclaimed. The Son is similar to the Father (homoiousios), but not of the same substance (homoousios) as the Father. He is a divine being, but a subordinate one.  In some ways, it is a deceptively simple argument: the father always precedes the son. Therefore, the Father existed before the Son.

This logic would seem irrefutable and confirmed a strict 'monotheism' by offering a rational explanation for Christ's human experiences of suffering and limitation.

However, at the Council of Nicaea (CE 325), summoned by Constantine to ensure unity within the nascent Church establishment, and under the influence of Arius’s arch-rival Athanasius, the Patriarch of Alexandria, Arius was condemned as a heretic.  The Council fudged logic by declaring the Son was "begotten, not made" and "of one substance (homoousios) with the Father." To deny the Son's full divinity, they argued, was to make our salvation the work of a creature, not God Himself.

Arianism was to fracture the Empire for decades, enjoying patronage from several emperors. It eventually faded within the Roman world but was successfully preached to Germanic tribes like the Goths and Vandals, shaping early medieval Europe's religious map.

Donatism

In the wake of the Diocletian persecution (CE 303-305), a practical crisis in North Africa sparked a theological conundrum: could the Church accept those clergy who, in the face of persecution, had apostatised or collaborated with the Roman authorities, be accepted back into the Church? Professed by Donatus Magnus, the Donatists argued that the holiness and validity of the sacraments (like baptism and ordination) depended on the personal moral purity of the priest. Priests and clergy, who betrayed Christianity or had handed over scriptures to Roman authorities (traditores), were permanently disqualified. Their sacraments were invalid, and their churches were not the true Church.

Donatism offered a vision of the Church as a righteous remnant, uncorrupted by compromise with a sinful world. It was also a North African regional movement that shunned the authority of Alexandria and so was extremely popular among Berber communities and the urban poor of Carthage.

The counter view, proposed by theologians like Augustine of Hippo, argued that the ‘efficacy’ of a sacrament depends not on the priest's worthiness, but on Christ's authority and the faith of the recipient. This view is based on the principle "ex opere operato" (the work comes out of the work done).  It should also be recognised that the Christian Church is a "mixed body" (corpus permixtum) of saints and sinners until the final judgment.

Over time, Donatism was suppressed by imperial force, but its core question, the relationship between institutional authority, personal holiness, and grace, recurs throughout Church history, from the medieval Waldensians to the Protestant Reformation.

Pelagianism

As the Church settled into the social mainstream in the 5th century, a British monk named Pelagius reacted against moral laxity. His emphasis on human responsibility, however, escalated into a full-blown controversy over the nature of sin and grace. Pelagius taught that human nature was essentially undamaged by Adam's sin. We sin by freely imitating Adam's example, not because we inherit a corrupted nature. Therefore, we have the perfect capacity to choose good and fulfil God's law by our own willpower. Divine grace is a helpful external aid (like Christ's teaching or the law), but not an internally necessary power. It affirmed human dignity, moral responsibility, and the rationality of God's commandments.

Augustine of Hippo was a fierce opponent of Pelagius. Augustine, elaborating on Paul’s view, argued that the original sin of Adam and Eve had wounded human nature itself, enslaving the will. We can not sin (non posse non peccare) without an internal, transforming gift of grace, which is unmerited and predestined by God. Salvation is entirely God's work. Augustine rejected human free will because the omnipotent and omniscient God bestows salvation through grace, which is beyond human understanding.

The Church took Augustine’s mystical position, laying aside rationality and condemned Pelagius at the Council of Ephesus (CE 431). Though the concepts of Pelagianism suffered a major blow, a moderated form ("Semi-Pelagianism") persisted. The debate was to fundamentally frame Western Christian anthropology, as it became the basis for further debate, for example, in the Reformation with arguments between Luther and Erasmus.

As you might expect from a modern perspective, when I organised a debate in the St Albans Cathedral between Augustine and Pelagius on the validity of the concept of Original Sin, Pelagius' concept of free will and his denuciation of original sin won the debate hands down.

Nestorianism

Nestorius, Archbishop of Constantinople from 428 to 431, sought to protect Christ's full humanity, so he taught that in Christ there were two distinct subjects: the divine Logos and the human Jesus, united in a sympathetic union, but not a single personal union. He feared that saying "God suffered" was heresy (theopassianism). This position meant that he rejected the term Theotokos ("God-bearer") for Mary, preferring Christotokos ("Christ-bearer"). It provided a clear, logical way to distinguish divine and human attributes (communicatio idiomatum), preserving the integrity of both natures.

However,  Cyril, Patriarch of Alexandria  (412 – 444), argued that salvation required one single, divine person who truly experienced human life and death. The Council of Ephesus (431) confirmed Mary as Theotokos and upheld what they called the hypostatic union: two natures (human and divine) inseparably united in one person, Jesus Christ.

Nestorius was expelled from the Empire but found a lasting home in the Persian (Sassanid) Empire, and Nestorianism spread across Asia as far as China, so that his Christological doctrine survived for centuries.

Heresies forced the Church to wrestle with very real questions about the nature of the Christian faith. These four heresies were not fringe curiosities; they were live options that attracted emperors, intellectuals, and masses of the faithful.

4. Heresy and Christendom

In the centuries after the foundational Christological and Trinitarian controversies, the Church in Mediaeval Europe and the Eastern Roman Empire (Byzantium) would face new waves of dissent that tested not only doctrine but also the very relationship between faith, image, and power.

Monothelitism 

In the 7th century CE, as the Byzantine Empire reeled under Persian and Arab invasions, Emperor Heraclius (410-461) sought a theological formula to reconcile the fractious Christian factions of the Eastern Empire, especially the Monophysites, who believed Christ had only a divine nature. Desperate for a compromise, the Patriarch of Constantinople, Sergius, proposed Monothelitism (from Greek: mono- "one," thelema "will"). It accepted the orthodox doctrine of Christ’s two natures (human and divine) but argued there could only be a single, divine will.

This seemingly subtle distinction was doomed to fail as opponents argued that if Christ lacked a human will, humanity’s salvation was incomplete as the human soul will would not be redeemed. After Heraclius’ time, the controversy was finally settled at the Third Council of Constantinople (680–681), which condemned Monothelitism and affirmed Dyothelitism (two wills): Christ possessed two natural wills, divine and human, "without division, without change, without separation, without confusion." The concept of Monothelitism disappeared, a testament to the failure of the compromise of political theology to override theocratic doctrinal precision.

Iconoclasm 

If Monothelitism was a crisis of will, Iconoclasm (Greek: "image-breaking") was a political crisis of practice. In the 8th century, with the Byzantine Empire ravaged by Arab attacks, a military commander, Leo III, from the mountainous and borderland area of Isauria, seized the throne. He launched a violent campaign to destroy religious icons: paintings, mosaics, and statues of Christ, Mary, and the saints. He and his dynasty seemed to be motivated by a mix of Islamic influence, militaristic piety, and a reaction against the perceived superstition of the monastic orders. Iconoclasts argued that veneration of icons was idolatry, violating the Second Commandment.

The defence of icons, championed by theologians like John of Damascus, drew a crucial distinction: veneration (dulia) offered to icons was not the worship (latria) due to God alone. It was argued that icons were windows to the divine, affirming the incarnation, as God took material form in Christ, it was right that he could be depicted. The dispute raged for over a century, culminating in the victory of the Iconophiles (‘lovers of icons’) at the Second Council of Nicaea (787), which restored icon veneration. Iconoclasm’s legacy was profound: it solidified the Eastern Church’s theology of images and deepened the divide with the West, which had not engaged with Iconoclasm.

Paulicianism 

In the shadow of the Iconoclastic controversy, a far more radical dissent was emerging on the fringes of the Empire. These were dualist heresies that rejected the material world itself as the creation of an evil god. One was known as the Paulicians (7th–9th centuries, based in Armenia and Anatolia): they rejected the Old Testament, the sacraments, and the institutional Church. They saw the material world as the creation of the evil Demiurge (the God of the Old Testament) and worshipped only the God of the New Testament. Persecuted fiercely by Byzantium, they often sided with Muslim armies, viewing them as lesser evils than the "orthodox" empire.

Bogomilsm 

It is thought that Paulicians, defeated by Byzantium, were forcibly moved to the Bulgarian border and emerged during the 10th–14th centuries, as the Bogomils ("Beloved of God"). They preached a stark dualism: the visible world was Satan’s kingdom; the invisible, spiritual world belonged to God. They rejected the symbol of the Cross (believing it to belong to the Devil), the Eucharist, marriage, and meat-eating. Their ascetic elite, the "Perfecti" lived as wandering preachers, attracting widespread support from the poor but also influencing the nobility. The movement spread throughout the Balkans and was seen as a major threat to the established Church.

Catharism 

The Bogomil message travelled trade routes to Italy and southern France, where it blossomed as Catharism (from Greek katharoi, "the pure"). In Languedoc, the Cathars built a parallel church with their own bishops, rituals, and moral system. They divided followers into the ascetic, celibate Perfecti and the ordinary Credentes (Believers). The Cathars' rejection of the Catholic Church, its sacraments, and its materialism appealed to nobles and commoners alike, threatening papal authority. The response from the Catholic Church was brutal: the Albigensian Crusade (1209–1229) – named after the city of Albi was a twenty-year war of annihilation sanctioned by Pope Innocent III.  One of the most notorious episodes was the massacre (1209) of all the citizens of Beziers. When the besiegers attacked the city, it is reported that the leader of the Catholic forces, Arnaud Amalric, a Cistercian Abbot, was asked how the soldiers should treat the citizens, as there would be Catholics among the Cathars; he replied, "Kill them, for the Lord knows those that are His" (Caedite eos. Novit enim Dominus qui sunt eius). Even if the anecdote is untrue, the tone of the command reflects the total inhumanity and brutality of the ‘crusade’. The massacre of Bezkiers was not an isolated incident: in 1242, around 220 Cathars were burned alive in a bonfire at the foot of the fortress Montségur when they refused to renounce their faith.

Alongside the military campaign against the Cathars, Pope Gregory X established the Inquisition to uproot heretical movements and carry out a systematic hunt for non-Christians.

The Cathars were exterminated, but their story became a symbol of medieval religious repression.

The heresies of Monothelitism, Iconoclasm, Paulicianism, and the dualist traditions of the Bogomils and Cathars represent pivotal crises that shaped the mediaeval Christian East and West. Each of these heretical movements forced the institutional Church to clarify its teachings, often through imperial intervention and ecumenical councils, revealing the deep tensions between spirituality, authority, and the human desire for a purified faith. In crushing these movements, the mediaeval Church defined its boundaries with unprecedented force. The defeat of Iconoclasm affirmed the sacramentality of matter. The extermination of the Cathars demonstrated the lethal power of orthodoxy when allied with the state. Yet, the dualist longing for a pure faith never fully died, echoing later in Protestant asceticism and modern ideological puritanism.

5. Cult, Sects and Movements

The landscape of Christianity has been reshaped not only by the heresies of the early Church but by successive waves of dissent and reform that have challenged the theological, political, and cultural authority of the dominant Christian tradition.

Waldensians:

In the late 12th century, a wealthy merchant of Lyon named Valdes (Peter Waldo) underwent a conversion, gave away his possessions, and began preaching a life of voluntary poverty and literal adherence to the Gospel. His followers, the “Poor Men of Lyon” or Waldensians, emerged decades before the Protestant Reformation as a formidable dissenting movement. Rejecting the hierarchical and sacramental authority of the mediaeval Catholic Church, they emphasised lay preaching, vernacular scripture, and simple piety. They denied purgatory, prayers for the dead, and many traditional sacraments, insisting that the Bible alone was the rule of faith.

In 1179, Waldo visited Pope Alexander III in Rome and criticised the Church for its excesses, corruption and dogma. The following year, the Waldensians were expelled from Lyon and in 1184, at the Council of Verona, Pope Lucius III excommunicated the movement. 

For centuries, the Waldensians were hunted as heretics, surviving in remote Alpine valleys. Their endurance through severe persecution, including the infamous 1655 “Piedmont Easter” massacre, made them symbols of religious resistance. Remarkably, after the Reformation, many Waldensians aligned with Swiss Calvinism, becoming a Protestant church that survives in Italy and the diaspora to this day. They represent a crucial bridge between mediaeval dissent and the Reformation, embodying the perennial demand for a simpler, more biblically-centred faith.

Protestantism

Beginning in 1517 with Martin Luther’s Ninety-Five Theses against the Catholic Church, Protestantism erupted as a theological, political, and cultural earthquake that shattered the unity of Western Christendom. It was not a single movement but a constellation of reforms united by core principles, known as the ‘Solas’ (Only):

• Scripture Alone: the Bible is the sole infallible source of doctrine.

• Faith Alone: Salvation comes by God’s grace through faith in Christ.

• Grace Alone: only God’s Grace - omnipresent and omniscent'

• Christ alone: not through the Priesthood.

• God Alone: all believers have direct access to God.

From Lutheranism and Calvinism to the radical Anabaptists and later Puritans, Protestantism diversified into numerous denominations and triggered wars (like the Thirty Years’ War), fueled nationalism, and transformed Western society by promoting literacy, individualism, and new economic ethics. While internally diverse, Protestantism collectively established a permanent alternative to Roman Catholicism, defining itself by its rejection of papal authority and its return to “primitive” Christianity.

Mormonism (Church of Jesus Christ of Latter-day Saints)

Born in the “burned-over district” ( a term coined by revivalist preacher Charles Grandison Finney, describing an area saturated with intense religious revivals) of upstate New York during the American Second Great Awakening, Mormonism was founded by Joseph Smith in the 1820s. Smith claimed to have been led by an angel (Moron) to ancient golden plates, which he translated by divine power as the Book of Mormon, an account of ancient Hebrews in the Americas. Mormonism presents itself not as a reform of existing Christianity but as a complete “restoration” of the original Church, which it claims fell into total apostasy after the death of the Apostles.

The Mormons' key ordinances are:

• Baptism: including baptism for the dead.

• Confirmation: a ceremony by which you become a member of the church.

• Endowment: adult members may receive a "gift" of knowledge, power, and promises from God.

• Marriage: including polygamy.  

• Patriarchal Blessing: a personal message from God from a church senior.

• Continuing Revelation: living prophets (the Church President) receive ongoing divine revelation.

Persecuted for its theocratic aspirations and (ostensibly now-abandoned) practice of polygamy, the Mormons migrated to Utah, where it grew into a global, highly organised, and culturally distinct faith. Mainstream Christianity, both Catholic and Protestant, classifies Mormonism as non-Trinitarian and therefore heterodox, due to its radical redefinition of God and its addition of a scripture.

Jehovah’s Witnesses

Emerging from the Bible Student movement of the late 19th century, Jehovah’s Witnesses were organised by Charles Taze Russell and later Joseph F. Rutherford. They are defined by their ardent millenarianism (primarily from the Bible's Book of Revelation, referencing a 1,000-year reign), rejection of mainstream Christian doctrines, and intense separatism from “the world.” Their core beliefs are:

• Theocratic Organisation: a strictly hierarchical, centralised leadership with no clergy-laity distinction.

• Anti-Trinitarianism: they are staunchly unitarian, viewing Jehovah (the Father) as the only true God. Jesus is the created archangel Michael; the Holy Spirit is God’s impersonal active force.

• Pacifism and Political Neutrality: they refuse military service, voting, and patriotic rituals.

• Eschatological Urgency: they believe they are living in the final days before Armageddon, after which a righteous theocratic kingdom will rule the earth. Only 144,000 “anointed” Witnesses will go to heaven; the rest of the faithful will live forever on a paradise earth.

Known for their door-to-door evangelism and refusal of blood transfusions, Jehovah’s Witnesses are often viewed as a high-control sect by outsiders. Like Mormons, they are considered non-Christian by orthodox standards due to their denial of the Trinity and the full divinity of Christ. Their history is marked by legal battles over religious liberty, which have shaped modern First Amendment jurisprudence in the USA.

These four movements: the Waldensians, the Protestant Reformation, Mormonism, and Jehovah’s Witnesses represent pivotal moments in the history of Later Christianity. Spanning from the 12th century to the modern era, each began as a radical break from the religious establishment, offering alternative visions of scripture, authority, and salvation. While their historical contexts and theological claims differ dramatically, together they illustrate the ongoing tension between orthodoxy and innovation, institution and inspiration, in the Christian world.

They also reveal a pattern in the history of religious innovation: each began as a radical critique of the prevailing religious establishment, offering a return to a purer, more authentic form of faith. The Waldensians and Protestants sought reform within the framework of historical Christianity, appealing to the early Church and scripture. The Mormons and Jehovah’s Witnesses, by contrast, presented themselves as unique restorations, introducing new scriptures and revelations.

They highlight the evolution of religious tolerance. The Waldensians faced massacre; Protestants fought wars of religion; Mormons were driven into the desert; Jehovah’s Witnesses endured mob violence and Supreme Court battles. Yet, each has persisted, carving out a distinct identity in the global religious landscape.

Ultimately, the story of these movements is the story of Christianity’s relentless capacity for self-reinvention. They remind us that “orthodoxy” is often defined in opposition to what it excludes, heresies, and that the quest for religious truth is a dynamic, contested, and ever-unfolding intellectual drama.