Q & A of the Catholic Faith: The Oldest Catholic Church in the World: Does It Prove the Catholic Church Is the True Church?

Description

Does the oldest Catholic cathedral still in use prove Catholicism is the original Church of Christ? Discover the historical evidence, biblical foundation, Church Fathers, apostolic succession, and Catholic answers to Protestant objections—complete with timelines, charts, and an infographic.

Introduction: A Common Protestant Challenge

Protestants often ask:

“If the Catholic Church is the true Church founded by Jesus, where was it in the early centuries?”

Or more directly:

“Owning the oldest church building doesn’t prove you’re the true Church!”

Fair point—a building alone is not the whole proof.
But the existence of ancient Catholic cathedrals does matter, because it supports a bigger claim: historical continuity.

In this article, we’ll examine how the oldest Catholic cathedral still functioning becomes a powerful piece of evidence when combined with Scripture, early Christian writings, and apostolic succession.

The Oldest Catholic Cathedral Still in Use: Saint Domnius, Split (Croatia)

Key Historical Facts

✅ Cathedral of Saint Domnius (Split, Croatia) is widely regarded as the oldest Catholic cathedral still in use in its original structure.

It was consecrated as a Christian cathedral around the turn of the 7th century

Important nuance: The structure is ancient, but its use as a cathedral developed as Christianity became legal and publicly established across the empire.

Does the Oldest Catholic Church “Prove” the True Church?

The Short Answer (Balanced)

✅ It helps a lot
❌ but it’s not a stand-alone proof

A building can’t prove everything—but it can confirm visibility and historical continuity, which is part of Christ’s promise.

Why it Matters Apologetically

The oldest Catholic cathedral is evidence of continuity, not merely “old architecture.”

It supports this claim:

The Catholic Church is not a later invention—it is historically rooted in the earliest centuries and remained visible through time.

Biblical Foundation: Christ’s Church Must Endure and Remain Visible

1) Christ Established One Enduring Church

“You are Peter, and on this rock I will build my Church, and the gates of Hades shall not prevail against it.”
Matthew 16:18

If Christ built a Church that cannot be overcome, then we should expect continuity, not disappearance.

2) The Church Is Meant to Be Visible

“A city set on a hill cannot be hidden.”
Matthew 5:14

A purely invisible “true Church” that cannot be traced historically is hard to square with a Church meant to be publicly known in the world.

3) The Faith Must Be Handed Down Through Authorized Leaders

“What you have heard from me… entrust to faithful men who will be able to teach others also.”
2 Timothy 2:2

That is succession language: teaching transmitted through appointed ministers.

Quote Box: The “Oldest Church” Is Not Just About Stone

Buildings don’t create the Church—Christ does.
But ancient Catholic churches demonstrate something crucial:
the same Church remained present, organized, and worshiping through time.

Apostolic Fathers & Church Fathers: Early Christianity Looks Catholic

Protestants sometimes assume Catholic structure developed much later, but the earliest Christian writers already describe:

✅ bishops
✅ visible Church authority
✅ Catholic identity
✅ Eucharistic faith and unity

1) St. Ignatius of Antioch (A.D. ~107)

Ignatius—student of the apostolic age—famously wrote:

“Wherever the bishop appears, there let the people be; as wherever Jesus Christ is, there is the Catholic Church.”
Letter to the Smyrnaeans 8

That’s early (near-1st century Christianity) using the term “Catholic Church” and emphasizing bishop-centered unity.

2) St. Irenaeus of Lyons (A.D. ~180): Apostolic Succession

Irenaeus refuted heretics by pointing to churches that preserved doctrine through succession of bishops.

That means the “true faith” was not decided by personal interpretation alone—but by continuity from the apostles.

CCC Teaching: Apostolicity Is a Mark of the True Church

The Catholic Church teaches that Christ’s Church is apostolic in three ways:

founded on the apostles
preserves their teaching
governed by successors of the apostles (bishops)

This is exactly what Scripture and Fathers describe.

Historical Timeline: From Christ to Ancient Cathedrals

🕰️ Timeline of Continuity

A.D. 30–33 – Christ dies and rises
A.D. 33 – Pentecost: Church publicly begins (Acts 2)
A.D. 90–110 – Apostolic Fathers (Clement, Ignatius) describe authority and unity
A.D. 180 – Irenaeus teaches apostolic succession as proof against heresy

A.D. 305 – Saint Domnius structure built (Roman era)

7th century – Cathedral consecrated and used as Catholic worship space

Today – Still functioning as Catholic cathedral

Development/Evolution: Did Catholicism “Change”?

A fair Protestant claim is:

“Catholicism evolved—therefore it isn’t the original Church.”

But there’s a difference between:

✅ Development (growth in clarity and public expression)
vs
❌ Corruption (changing the apostolic faith)

Example

Early Christians already had:

bishops (Ignatius)

succession as proof (Irenaeus)

visible unity and authority

What changed later was not the essence of the Church—but its legal freedom, public buildings, and global scale.

So yes, the Church “developed” outwardly—because Christianity moved from persecution → public worship.

The Strongest Catholic Argument: Old Churches Support the Bigger Case

Here’s the strongest way to explain it:

✅ Oldest Catholic churches help prove:

the Church remained visible
the Church remained organized
Catholic worship existed early and continuously
Christianity did not “restart” in the Reformation era

But the full proof comes from a combination of:

✅ Scripture (Christ built one enduring Church)
✅ early Fathers (Catholic identity & authority already present)
✅ apostolic succession (continuity of leadership)
✅ historical visibility (the Church can be traced)

Conclusion: Is It Evidence the Catholic Church Is the True Church?

✅ Yes—strong supportive evidence
But it becomes truly powerful when paired with the deeper foundation:

Christ founded a Church (Matthew 16:18)
The Church remains visible (Matthew 5:14)
Apostolic teaching is transmitted through authorized leaders (2 Tim 2:2)
Early Christians recognized the Catholic Church and bishops (Ignatius)

So the oldest Catholic cathedral isn’t the whole argument—
but it is a compelling historical witness that the Catholic Church is not new, not invented later, and not invisible.

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Friday, January 23, 2026

The Oldest Catholic Church in the World: Does It Prove the Catholic Church Is the True Church?