Church History · Lesson 5

God and Man

The Council of Chalcedon, 451 — and the capstone of the question "Who is Jesus?"

📍 You are here: Era 1 · The Early Church — closing the "Who is Jesus?" arc.

Why this matters for you: Nicaea answered "Is Jesus God?" (yes). But that raises a harder one you'll meet constantly when teaching: "If he's fully God, how is he also a real human who got tired, wept, and died?" Chalcedon is the church's careful answer — and, as you'll see, it uses the exact same toolkit you already learned.

You already have the tools. Remember hypostasis hoo-POSS-ta-sis = person ("who"), and ousia oo-SEE-ah = being ("what"). One new word today: physis FOO-sis = nature (the "kind of thing" something is — its set of properties). Chalcedon is built entirely from these.

By the 400s the deity of Christ was settled. The new fight: how do the divine and the human fit together in the one Jesus? Once again, two opposite ditches — and once again, a narrow road between them.

◀ Ditch 1 · Nestorianism

Splits Jesus into two

The divine and human are so separated they're almost two persons sharing a body — "two boards glued together."

Nestorius refused to call Mary Theotokos theh-oh-TOH-kos ("God-bearer"), only "Christ-bearer" — implying the baby wasn't truly God.

"Two persons, loosely joined."

✗ Divides the one person

● The narrow road · Chalcedon

One person, two natures

One person (hypostasis) who is fully God and fully man — two complete natures (physeis) united in him, neither blurred nor torn apart.

So Mary truly is Theotokos: the one she bore is God the Son.

"Fully God, fully man, one person."

✓ Holds both natures AND the one person

Ditch 2 · Eutychianism ▶

Blends Jesus into one

Eutyches YOO-tih-keez: Christ has only one nature — the humanity is swallowed up by the divinity "like a drop of honey in the sea."

Also called Monophysitism mon-OFF-ih-sih-tism (mono = one, physis = nature).

"One blended nature."

✗ Loses the true humanity

Nestorius divides the person · Eutyches blends the natures · Chalcedon keeps one person in two natures.

The toolkit (one new word)

physis (φύσις) FOO-sis

"nature" — the kind of thing something is

Jesus has two: a divine nature and a human nature. (Plural physeis, FOO-sayes.)

hypostasis (ὑπόστασις) hoo-POSS-ta-sis

"person" — the concrete "who" (from Lesson 4)

Jesus is one of these — one person, one "I."

The whole formula in a breath: Jesus is one hypostasis (person) in two physeis (natures). Nicaea counted the ousia; Chalcedon counts the physeis.

The Chalcedonian Definition (451) — the four famous "withouts"

"…one and the same Christ… made known in two natures without confusion, without change, without division, without separation…"

without confusion — the natures aren't blended → refutes Eutyches

without change — neither nature is altered → refutes Eutyches

without division — not split into two persons → refutes Nestorius

without separation — never come apart → refutes Nestorius

Two adverbs guard each ditch. The first pair fences out blending; the second pair fences out splitting. → 500+ bishops; guided by Pope Leo I's letter ("Leo's Tome").

"Two Natures unconfusedly, unchangeably" refutes Eutychianism; "indivisibly, inseparably" and "Theotokos" are against Nestorianism. — Chalcedonian Definition (overview); see also Catholic Encyclopedia: Council of Chalcedon

Honest history — the first lasting split: Not everyone accepted "two natures." Churches that held to "one (united) nature" language broke away and survive today as the Oriental Orthodox — the Coptic (Egypt), Armenian, Ethiopian, and Syriac churches. So Chalcedon both settled the doctrine for most of the church and caused Christianity's first major enduring division — five centuries before the East–West split of 1054. (New World Encyclopedia)

Practice: which ditch (or the road)?

Classify each statement. Instant feedback below.

Nestorianism Chalcedon Eutychianism

Score: 0 / 7

Ask me anything

Want to know why this even mattered for salvation (hint: "what he didn't assume, he didn't heal")? Curious what "Leo's Tome" actually said, or who the Oriental Orthodox are today? Or how Mary being Theotokos is a statement about Jesus, not mainly about Mary?

That closes the "Who is Jesus?" arc — you now have Nicaea, the vocabulary, and Chalcedon. Say next and we can step back to see Era 1 whole, or cross into Era 2 via the filioque and the road to 1054.