“Dwell on the past and you will lose an eye. Forget the past and you will lose both eyes.” – Russian Proverb

There is a peculiar irony in our time: while some corners of the Christian world are quick to cry heresy over every theological disagreement, many seem less certain about what the historic heresies even were—or why they mattered. In Know the Heretics, Justin S. Holcomb invites us to travel through the theological fault lines of early Christianity, not merely to gain historical insight, but to understand the foundations of orthodoxy itself.

This isn’t just a theological museum tour. It’s more like boarding the Heart of Gold—you’re never quite sure what direction you’re heading in, but the journey itself is unexpectedly enlightening. The book deftly avoids a spirit of condemnation or tribalism. Instead, it seeks understanding—of how theology was shaped, clarified, and ultimately protected.

The Importance of the Heretic

Let’s suppose you had never heard of Nestorius or Arius or even the Docetists. Would it matter? For Holcomb—and, indeed, for the Church Fathers—it matters profoundly, because their wrong answers forced the Church to clarify the right questions.

Heretics were not often malicious cartoon villains twirling theological mustaches. Many were sincere, passionate, and intellectually robust. But sincerity is not orthodoxy. As Holcomb emphasizes, heresy is often an oversimplification of divine mystery. It is not doubt that makes a heretic, but dogmatic answers that distort the truth.

“People are not heretics because they ask questions; it is the answers they give that are wrong.”

Orthodoxy, then, is not simply a majority opinion or historical accident. Contra Walter Bauer’s 1934 revisionist theory that the “winners wrote the creed,” Holcomb underscores the idea of authentic inheritance—a faith received, tested, and defined in fidelity to Scripture, not institutional power.

Chapter Highlights: A Travel Guide Through Trouble

Each chapter of Know the Heretics examines one particular heresy, explaining its historical roots, its core teaching, the orthodox response, and its lingering modern echoes. Here are a few stops on the itinerary:

Judaizers – Grace vs. Law

Legalism isn’t new. The earliest heresy Paul addressed was from those who wanted to keep the old Jewish law alongside the gospel. It sounds quaint—until you realize that many modern churches still flirt with performance-based salvation. It’s the same plotline, different century.

Think of it like the Ghostbusters sequel where they try to franchise the concept—same brand, new city, but the ghosts of legalism keep returning.

Gnostics – Secret Knowledge and the Hatred of Matter

A heresy tailor-made for a Netflix miniseries. The Gnostics believed in secret spiritual knowledge and saw the physical world as evil. Their Jesus was a ghostly liberator, not a suffering savior.

Today, you can still hear faint Gnostic whispers when people describe spirituality as “freeing your inner light” or talk about heaven as an escape from the material. Holcomb rightly shows why the incarnation—God with us, in flesh—was such a scandal, and why it’s still the Church’s anchor.

(Bonus points if you caught the theological tension with the Force in Star Wars, where the physical is often downplayed in favor of the mystical. “Luminous beings are we—not this crude matter,” said Yoda. The Gnostics would’ve loved him.)

Marcion – The Bible Editor-in-Chief

Marcion rejected the Old Testament and trimmed the New Testament down to fit his theology. A 2nd-century Thomas Jefferson, but with less Enlightenment and more dualism. His edited Bible was Jesus-only, without the “angry” God of the Old Testament.

But here lies the genius of orthodoxy: in keeping both Testaments, Christianity holds together God’s justice and mercy. It prevents Jesus from becoming a warm fuzzy mascot disconnected from the God who thunders from Sinai.

“By retaining the Old Testament the church scored two important points. First, it is insisted that faith for the Christian world have to reconcile both the wrath and love of God.” “Christ’s death, he said, allowed God to be both just and the justifier of all who believe in Jesus (Rom 3:25-26). That is the marvel of the grace of God Marcion missed.”  Bruce Shelley

Docetism, Sabellianism, Arianism, Nestorianism…

Holcomb explores each heresy with care, and always connects it back to the implications for today. Whether it’s Docetism’s denial of Christ’s humanity, Arianism’s demotion of Christ’s divinity, or Nestorius’s awkward theological two-step that risked splitting Christ in half—each error gives the Church a chance to say: No. This is what we believe. And this is why it matters.

Modern Echoes: The Heresies That Never Quite Died

You might say, “Okay, but who really believes these things anymore?”

Well, you might be surprised. Oneness Pentecostals echo Sabellius. Prosperity gospel preachers promote a kind of Pelagian self-help theology. Some liberal theologians mirror Socinus in making Jesus only a moral example. And everyday Christians casually parrot Marcion when they say things like “I prefer the God of the New Testament.”

In pop culture, you see Docetism every time a show makes Jesus look like a serene space-angel (think Paul Atreides in Dune) untouched by dust, blood, or doubt. It’s harder to portray a sweaty, crying, bleeding God. Yet that’s the very image the Gospels present.

Why This Book Matters Now

We live in an age where deconstruction is in vogue and chronological snobbery (to borrow C. S. Lewis’s phrase) tempts us to believe we’ve evolved past the need for creeds. But Holcomb’s work is a kind of theological treasure map—leading us through ancient booby traps, warning us about theological pitfalls, and encouraging us to not give up on the treasure of truth just because some old guy named Chester Copperpot died trying.

Modern Heresies: Jehovah’s Witnesses and the Echoes of Arius

What’s the point of dusting off old theological debates about Arius or Apollinaris? Aren’t these just arcane footnotes for history nerds and seminary students?

Well, you might say that. But if you’ve ever spoken with a Jehovah’s Witness at your door, you’ve actually stepped right into the middle of one of these ancient arguments—specifically, the one involving Arius in the 4th century. The question they raise is the same: Is Jesus fully God, or is he a lesser, created being?

Jehovah’s Witnesses argue that Jesus is not co-eternal with the Father, but rather the first and greatest creation of Jehovah—exalted, yes, but not divine in the same way. To them, he is a god but not the God. Sound familiar? That’s because it is.

Arius of Alexandria would have felt right at home in a Kingdom Hall.

Why This Matters: The Necessity of the God-Man

Let’s suppose Jesus were not fully divine. Let’s say, for the sake of argument, he was the greatest created being—sinless, wise, even miraculously empowered—but still created. What then?

The answer strikes at the very heart of the gospel.

1. Only God can overcome the infinite offense of sin.
   Sin is not just a moral failing—it is rebellion against an infinitely holy God. A finite creature, no matter how exalted, cannot bear the weight of infinite justice. The sacrifice must be of infinite worth. That’s why Jesus must be God.
2. Only a human can truly represent humanity.
   But let’s suppose Jesus was God only, pretending to be human (hello again, Docetism). In that case, he wouldn’t have truly entered into our human condition. He couldn’t weep, hunger, thirst, suffer, or die—not really. He couldn’t be the second Adam (Romans 5:12–21), the one who stands in our place as a substitute. That’s why Jesus must also be fully man.

To reconcile God and humanity, Jesus must bridge both realities. The Council of Chalcedon (451 AD) captured this mystery with exquisite clarity: he is “recognized in two natures, without confusion, without change, without division, without separation.” This is not theological abstraction—it’s the essence of Christian salvation.

“He became what we are so that He might make us what He is.” — Irenaeus

The Practical Problem with a Lesser Jesus

If Jehovah’s Witnesses are right and Jesus is a kind of “super-angel,” then we have a profound problem:

• The cross becomes a gesture, not a sacrifice of infinite value.
• The resurrection becomes a trick of divine power, not the triumph of God over death from within death.
• Salvation becomes merit-based, systematized, and hierarchical—much like what the Judaizers promoted.

And ironically, this view revives both the error of Arius (Christ is not of the same essence as the Father) and the Gnostics (Christ’s divinity cannot mix with flesh). It’s a hybrid heresy—ancient errors in modern dress.

Holcomb’s book shows us that this isn’t a matter of preference or personal interpretation. It’s a matter of orthodoxy—right teaching about who God is and how He saves. And the Church, through centuries of wrestling, landed on something beautifully mysterious: that Jesus is truly God and truly man, the only possible Savior of the world.

The Takeaway: Doctrine Isn’t Dusty—It’s Discipleship

When you know how the Church historically answered these heresies, you’re better equipped to respond to modern confusion. Whether it’s a pop culture Jesus who’s only a moral teacher, or a pseudo-Christian Jesus who’s merely exalted—not divine—the antidote is the same:

• Return to Scripture.
• Return to the creeds.
• Return to the God who revealed Himself, not just through words, but through incarnation.

So next time you open the door to a Jehovah’s Witness, don’t just see a debate—see a chance to return to the deep waters of Christian tradition. You might be surprised how well the early Church prepared you to swim.

Heretics (and Associated Movements or Ideas)

1. Judaizers – Legalism; insisted on adherence to the Mosaic Law (e.g., circumcision) for salvation
2. Gnostics – Denied the goodness of matter; secret knowledge for salvation; docetic Christ
   • Included groups like Valentinians, Ophites, Sethians, Cainites, Basilideans
3. Marcion – Rejected the Old Testament; dualistic theology separating OT God from NT Jesus
4. Docetists – Claimed Jesus only seemed human; denied the incarnation and suffering
5. Mani – Founder of Manichaeism; radical dualism of spirit vs. matter; Jesus not truly human
6. Sabellius – Modalism; claimed Father, Son, and Holy Spirit are different modes of one person
7. Arius – Denied Christ’s full divinity; claimed Jesus was a created being
8. Apollinarius – Taught that Jesus had a divine mind instead of a human rational soul
9. Pelagius – Denied original sin; taught that humans can choose good without divine grace
10. Eutyches – Claimed Christ’s divine and human natures merged into a third kind of nature
11. Nestorius – Over-emphasized Christ’s two natures; separated them into two persons
12. Socinus (Faustus Socinus) – Rejected the Trinity and original sin; saw Christ’s death as only an example

Theologians and Church Fathers Who Responded

1. Paul the Apostle – Responded to Judaizers in Galatians and Romans
2. Irenaeus of Lyons – Refuted Gnosticism and Docetism in Against Heresies
3. Tertullian – Countered Gnostics, Sabellianism; coined Trinitarian language (substantia, persona)
4. Hippolytus – Opposed Sabellianism and defended early Trinitarian thought
5. Origen – Contributed to early doctrine opposing Sabellianism and heretical views on the Trinity
6. Ignatius of Antioch – Insisted on Jesus’ real human suffering and death against Docetism
7. Polycarp of Smyrna – Contemporary of Ignatius; defended apostolic doctrine
8. Clement of Alexandria – Attempted to incorporate but also respond to some Gnostic elements
9. Athanasius of Alexandria – Strong opponent of Arianism; champion of Nicene orthodoxy
10. Gregory of Nazianzus – Opposed Apollinarianism; emphasized Christ’s full humanity
11. Augustine of Hippo – Refuted Pelagius; taught about original sin and divine grace
12. Cyril of Alexandria – Chief opponent of Nestorius; defended hypostatic union
13. Council of Chalcedon (451 AD) – Defined Christ as one person in two natures (against Eutyches)
14. The Cappadocian Fathers – Basil the Great, Gregory of Nazianzus, Gregory of Nyssa (helped refine Trinitarian theology)
15. Alexander of Alexandria – Opposed Arius before Athanasius took up the mantle

Conclusion: Heresy as a Gift (of Sorts)

“The disadvantage of men not knowing the past in that they do not know the present. History is an hill or high point of vantage, from which alone men see the town in which they live or the age in which they are living.” – G. K. Chesterton

Let’s suppose you found yourself in a theological argument and someone pulls out an obscure term like “hypostatic union.” Instead of panicking or retreating into vague spiritual talk, what if you could say, “Ah yes, Nestorius struggled with this too. Let me explain why it matters”?

Know the Heretics is more than a history book. It’s a mirror, a warning sign, and a toolkit.

Holcomb’s humility throughout the book is refreshing. He’s not trying to shame or divide. He’s trying to remind us: theology isn’t abstract. It’s incarnational. It’s about who God really is—and whether we’re willing to let Him be who He says He is.

And maybe, just maybe, embracing the mystery is better than explaining it away.

“We can apprehend God, but not comprehend Him.” – Tertullian

Resources

• Chalcedonian Box https://scriptoriumdaily.com/chalcedonian-box/
• Alister McGrath, Heresy A History of Defending the Truth
• Early Christian Writings, https://www.earlychristianwritings.com/

Excerpt

Ancient heresies aren’t just dusty debates—they shape today’s misunderstandings. Know the Heretics shows how early errors like Arianism and Gnosticism still echo in modern faith, reminding us why Jesus must be fully God and fully man. Orthodoxy isn’t rigid tradition—it’s the safeguard of a saving truth.