Church History · Lesson 2

Who Is Jesus?

The Council of Nicaea, 325 — and the one Greek word that defined Christianity.

📍 You are here: Era 1 · The Early Church (c. 30–590) — central question: Who is Jesus?

Why this matters for you: If you ever teach or disciple anyone, "Is Jesus really God?" is one of the first questions you'll meet. Nicaea is where the church answered it on the record — and the answer became the Nicene Creed that millions still recite every Sunday. Learn this and you understand the backbone of Christian belief about Jesus.

By the early 300s the church had a problem it could no longer dodge. Everyone agreed Jesus was divine in some sense. But exactly how was the Son related to God the Father? A priest in Alexandria forced the question into the open.

The spark. Arius, a popular presbyter (priest) in Alexandria, taught that the Son was the greatest of all created beings — but still created. There was, he said, a time before the Son existed. The slogan spread fast: "There was when he was not."

This split the church. So in AD 325, the emperor Constantine — recently converted, wanting unity in his empire — summoned around 300 bishops to the town of Nicaea (in modern Turkey) to settle it. It was the first ecumenical (church-wide) council.

Two answers to one question

✗ Arius — rejected

The Son is created

"There was when he was not."

Jesus is the first and highest creature, made by the Father. Exalted — but not eternal, not God in the fullest sense.

Protects God's oneness… but at the cost of Christ's full divinity.

✓ Nicaea — affirmed

The Son is eternal God

"True God from true God."

The Son was begotten, not made — eternally one with the Father, fully and truly God, not a creature.

This became the Nicene Creed, still recited in churches worldwide today.

ὁμοούσιος · homoousios /ho-mo-OO-see-os/

The decisive word the council chose: the Son is "of the same substance" (homo = same, ousios = being) as the Father. One word that drew the line: Jesus isn't like God or close to God — he is God, of the very same being as the Father.

This is the seed of the doctrine of the Trinity: one God in three persons — Father, Son, and Spirit — each fully God, yet one being. Nicaea nailed down the Son's side of that; the Spirit would be clarified soon after.

The creed affirmed that the Son is "homoousios," of the same substance as the Father, effectively condemning Arianism. — EBSCO Research Starters: Council of Nicaea

Honest history (this matters for teaching well): Nicaea didn't end the debate overnight. The popular idea that the Trinity was "decided in one meeting" oversimplifies — Arianism kept fighting back for decades, and it took Athanasius' lifelong defense and a second council (Constantinople, 381) to truly settle it. Real history is messier than the legend. (Britannica)

Practice: Arius or Nicaea?

For each statement, click whether it reflects what Arius taught or what Nicaea affirmed. Instant feedback below each.

Score: 0 / 6

Ask me anything

Want the actual words of the Nicene Creed? Curious how the Holy Spirit fits in, what "begotten not made" means, or who Athanasius was? Or how to explain Jesus' divinity to someone simply?

Just message me. When you're ready to move on, say next — we'll either go deeper in Era 1 (e.g. how the Bible's table of contents was settled) or jump to Era 2. Your call.