Heresies & Controversies

Matthew 13:24–43: The Weeds, the Mustard Seed, and a Field Left to Grow

A Catholic exegesis of Matthew 13:24–43: the parables of the weeds, mustard seed, and leaven, the Psalm 78 citation, and Augustine’s corpus permixtum.

Pope Saint Marcellinus: The Twenty-Ninth Pope, the Lapse Rome Tried to Forget, and the Council That Never Met

Marcellinus, the twenty-ninth pope (296–304), was accused of sacrificing to idols, erased from Rome's oldest calendars, and defended by a council that never met.

Pope Saint Miltiades: The Thirty-Second Pope, the Emperor's Peace, and the Schism It Could Not Heal

Miltiades, the thirty-second pope (311–314), lived from the last persecution into Constantine's peace, received the Lateran, and judged the first Donatist trial.

Pope Saint Eleutherius: The Thirteenth Pope, the Martyrs of Lyons, and the Legend of a British King

Eleutherius is the thirteenth pope (c. 175–189)—the deacon who became pope, correspondent of the martyrs of Lyons, and the pope a medieval legend made converter of Britain.

Jansenism: The Augustinian Heresy That Divided the Church

What was Jansenism? The Augustinian movement that became Calvinism in Catholic dress—the five propositions, Port-Royal, Pascal, and why Rome condemned it.

Nestorianism Explained: The Heresy That Made the Church Define Mary as Mother of God

Nestorianism split Christ into two persons and refused to call Mary Theotokos. Here is what Nestorius actually taught, how Ephesus answered, and why the 'Nestorian Church' is misnamed.

The Eunomian Heresy Explained: The Men Who Claimed to Know God’s Essence

Eunomianism, the radical Arianism of Aëtius and Eunomius, claimed God’s essence could be fully known—and was condemned at Constantinople in 381.

Marcellus of Ancyra and the Marcellian Heresy: Why the Creed Says His Kingdom Will Have No End

Marcellus of Ancyra fought Arianism so hard he fell into the opposite error—a Trinity that expands and contracts. The Creed's 'no end' clause answers him.

Photinus of Sirmium and the Photinian Heresy: When Christ Becomes a Mere Man

Photinus of Sirmium taught that Christ was a mere man, exalted but not preexistent. His name became the early Church's shorthand for denying the Incarnation.

The Pneumatomachian Heresy Explained: The Spirit-Fighters Who Forced the Creed’s Third Article

The Pneumatomachians ('Spirit-fighters') denied the Holy Spirit's divinity. Their challenge produced the third article of the Creed at Constantinople in 381.

Pope Saint Pius I: The Tenth Pope, the Brother of Hermas, and the Roman Church That Fought Marcion

Pius I was the tenth pope (c. 140–154), brother to Hermas of The Shepherd and the bishop under whom Rome expelled Marcion. No early source calls him a martyr.

Pope Saint Hyginus: The Ninth Pope, the Gnostic Crisis, and a Martyrdom the Sources Do Not Record

Hyginus, the ninth pope (c. 138–142), reigned as Valentinus and Cerdo brought Gnosticism to Rome. The martyr title attached to his name has no early source.

The Church of the East: Christianity’s Forgotten Fourth Branch

Christianity’s fourth apostolic branch—Mesopotamia to China. Apostolic origins, the 431 Christological controversy, missionary expansion, and witness today.

Donatism: The Ancient Heresy That Still Haunts the Church

Donatism, the fourth-century heresy that rejected sacraments from sinful clergy—and Augustine's ex opere operato answer, which still refutes it today.

Is Marian Devotion Idolatry? A Catholic Response to Protestant Objections

A charitable Catholic case for Marian devotion, answering Protestant objections from Scripture, the Fathers, and the Reformers themselves.

The Arian Heresy Explained: What Arius Taught and Why the Church Condemned It

What is Arianism? A Catholic guide to the Arian heresy — what Arius actually taught, why it was condemned at Nicaea, and why the debate over Christ's divinity still matters.

The Gnostic Gospels: A Catholic Guide to the Nag Hammadi Texts

What are the Gnostic Gospels? A Catholic guide to the Gospel of Thomas, Gospel of Philip, Apocryphon of John, and other Nag Hammadi texts—what they say and why they matter.

Gnosticism vs. Christianity: How the Ancient Heresy Distorted the Faith

How does Gnosticism differ from Christianity? A Catholic comparison of their views on God, creation, Jesus, salvation, scripture, and the body—and why it matters today.

What Is Gnosticism? A Catholic Guide to the Ancient Heresy

What is Gnosticism? A Catholic guide to proto-Gnostic currents, the 2nd-century systems, the Nag Hammadi texts, and the Church Fathers' response through canon, creed, and doctrine.

Five Heresies That Misread John 1 — and How the Church Answered Them

Five major heresies misread John 1: Arianism, Modalism, Adoptionism, Ditheism, and Docetism. Learn what each taught, where they went wrong, and how the Church's response was anchored in the text.

Modalism: The Trinitarian Heresy That Collapsed the Persons of God

What is Modalism? A Catholic examination of the heresy that denied the real distinction of Father, Son, and Spirit — its origins, key proponents, and why the Church condemned it.

Apollinarius of Laodicea and His Christological Heresy

Apollinarius of Laodicea denied that Christ had a human rational mind, replacing it with the divine Logos. Gregory of Nazianzus's devastating reply—'what is not assumed is not healed'—sealed the condemnation at Constantinople I (381).

Neo-Gnosticism in Evangelical and Progressive Christianity

How both evangelical and progressive Christianity have absorbed Gnostic tendencies—rejecting the body in different ways while departing from historic Christian teaching.