Valentinus
c. 100–160 • Alexandria → Rome
Core Error
Aeonic emanations, elitist gnosis, docetic drift undermining incarnation and creation’s goodness.
Damage
Elitism and denial of the goodness of creation; confuses the Incarnation and catholicity.
Key Opponents
Irenaeus, Tertullian
Marcion of Sinope
c. 85–160 • Sinope → Rome
Core Error
OT God distinct from Father of Jesus; rejects OT; truncates canon to edited Luke + 10 Paulines.
Damage
Severs Christianity from Israel; fuels anti-OT currents and canon distortion.
Key Opponents
Irenaeus, Tertullian
Montanus
2nd century • Phrygia
Core Error
Claims of new revelation superseding apostolic norm; prophetic ecstasy and rigorism.
Damage
Displaces Scriptural authority; fosters sectarian rigorism and instability.
Key Opponents
Asian synods, bishops in Rome
Sabellius
3rd century • Rome/Libya (traditions vary)
Core Error
One Person appearing in three modes; collapses personal distinctions in God.
Damage
Denies real Father/Son/Spirit distinctions; contradicts biblical triune relations.
Key Opponents
Hippolytus, Tertullian
Origen
c. 184–253 • Alexandria → Caesarea
Core Error
Pre-existence of souls; apokatastasis; extreme allegorism (nuanced, later receptions varied).
Damage
When radicalized by followers, seeds interpretive and doctrinal instability.
Key Opponents
Later anti-Origenist synods
Arius
c. 250–336 • Alexandria
Core Error
The Son is a highest creature—'there was when he was not'—denying co-eternity and consubstantiality.
Damage
Undercuts deity of Christ and Trinity; church-wide schism.
Key Opponents
Athanasius, Alexander of Alexandria
Pelagius
c. 360–418 • Britain → Rome → North Africa
Core Error
Denies original sin; human will can obey unaided; grace reduced to external help or example.
Damage
Erodes grace and necessity of inner renewal; moralistic soteriology.
Key Opponents
Augustine, African bishops
Nestorius
c. 386–451 • Antioch → Constantinople
Core Error
Over-separates natures in Christ leading to a 'two-persons' reading; disputes Theotokos.
Damage
Threatens unity of Christ’s person and the reality of the Incarnation.
Key Opponents
Cyril of Alexandria