A Guide to Roman Catholicism, Orthodoxy, and Protestantism
A Guide to Roman Catholicism, Orthodoxy, and Protestantism
Three Major Christian Traditions — What They Share and Where They Differ
Roman Catholics, Eastern Orthodox Christians, and Protestants all confess Jesus Christ, read the Bible, practice baptism and Communion, and trace their faith back to the early church. Yet they differ on authority, salvation, sacraments, church leadership, Mary, the saints, and how tradition relates to Scripture. Understanding those differences helps us speak more accurately—and more charitably.
Christianity is one faith, but Christians have not always agreed about how that faith should be understood and practiced.
Walk into a Roman Catholic Mass, an Eastern Orthodox Divine Liturgy, and a Protestant worship service, and you may feel as though you have entered three different worlds.
The architecture may be different.
The worship may sound different.
The leadership structure may look different.
The language used for salvation may differ.
The role given to tradition may differ.
Yet all three traditions identify themselves as Christian and claim continuity with the faith of the apostles.
The question is not whether differences exist. They do. The better question is what those differences actually are—and how significant they are.
The Three Traditions Have More in Common Than Many People Realize
Roman Catholicism, Eastern Orthodoxy, and historic Protestantism share many foundational Christian convictions.
Father, Son, and Holy Spirit.
Truly God and truly human.
The eternal Son became flesh.
Jesus died for our salvation.
Jesus bodily rose from the dead.
One God eternally existing in three persons.
The Bible is authoritative and inspired by God.
A central Christian initiation practice.
A central act of Christian worship.
Jesus will come again.
All three also affirm the great ecumenical creeds of the early church in some form, especially the Nicene Creed.
“Jesus Christ is Lord.”
Philippians 2:11, NIV
Before discussing the divisions, remember: these traditions share the central historical claims of Christianity.
A Very Short History of the Three Traditions
Christianity begins with Jesus, His apostles, and the earliest churches.
Major doctrines about Christ and the Trinity are clarified.
Eastern and Western Christianity formally divide, developing into Eastern Orthodoxy and Roman Catholicism.
Reformers such as Luther and Calvin challenge doctrines and practices in the Western church.
Roman Catholic, Eastern Orthodox, and Protestant Christianity continue as major global traditions.
The Three Traditions in Plain English
Scripture, Tradition, and the Teaching Church
Roman Catholicism emphasizes Scripture and apostolic tradition as authoritatively interpreted by the church’s teaching office, especially bishops in communion with the pope.
Scripture Within Holy Tradition
Orthodoxy sees Scripture as the heart of Holy Tradition, interpreted within the worship, councils, fathers, and continuing life of the historic church.
Scripture as the Final Authority
Protestantism generally teaches that Scripture is the church’s final infallible authority, while creeds, councils, and teachers remain valuable but subordinate.
Who Has the Final Authority?
This may be the most important difference between the three traditions.
Everyone agrees Scripture is authoritative.
The disagreement is over whether Scripture stands alone as the church’s final infallible authority.
“All Scripture is God-breathed and is useful for teaching, rebuking, correcting and training in righteousness.”
2 Timothy 3:16, NIV
The debate is not “Bible or no Bible.” It is how Scripture, tradition, and church authority relate to one another.
Scripture, Sacred Tradition, and the Magisterium
Roman Catholic theology speaks of Scripture and Sacred Tradition as one deposit of faith entrusted to the church.
The church’s teaching office is called the Magisterium.
Bishops teach in communion with the bishop of Rome—the pope.
Catholic theology therefore does not normally present authority as:
Bible versus tradition.
Instead, Catholicism sees Scripture, Tradition, and the church’s teaching authority as working together.
Protestants object that this can place later traditions alongside or functionally above Scripture.
Catholics respond that the same Spirit who inspired Scripture also preserves the church in faithfully handing on apostolic teaching.
Scripture Lives Inside Holy Tradition
Orthodoxy tends to speak less about separate sources of authority and more about one living Holy Tradition.
That tradition includes:
Scripture holds a unique and central place within that tradition.
Orthodoxy is suspicious of interpreting Scripture apart from the historical worshiping community that received and preserved it.
Sola Scriptura — Scripture Alone
The Reformation insisted that the final test of Christian doctrine must be the written Word of God.
That does not mean:
“Me, my Bible, and nobody else.”
Historic Protestants valued:
But all of them remain correctable by Scripture.
Protestantism does not reject tradition. It rejects the idea that tradition can become an infallible authority alongside Scripture.
How Are We Saved?
All three traditions confess that salvation comes through Jesus Christ and depends upon God’s grace.
But they often describe the relationship between grace, faith, works, justification, and sanctification differently.
Salvation is by God’s grace, received through faith, baptism, sacramental life, and a faith working through love.
Salvation is often described as participation in God’s life, healing from sin, and growing toward theosis.
Historic Protestantism emphasizes justification by grace alone through faith alone because of Christ alone.
This Was at the Heart of the Reformation
“Since we have been justified through faith, we have peace with God through our Lord Jesus Christ.”
Romans 5:1, NIV
Protestants classically distinguish justification from sanctification.
Justification is God’s declaration that the sinner is righteous because of Christ.
Sanctification is God’s continuing work of transforming the believer.
Catholic theology tends to speak of justification as including both forgiveness and inward renewal.
Orthodoxy generally places less emphasis on the legal categories of justification and more on transformation, healing, and union with God.
All three emphasize grace. The disagreement concerns what grace does, how justification should be defined, and how faith and obedience relate.
Do Good Works Save Us?
The answer requires careful wording.
Protestants say good works do not cause justification.
“For it is by grace you have been saved, through faith—and this is not from yourselves, it is the gift of God—not by works.”
Ephesians 2:8–9, NIV
But Protestants also insist that genuine faith produces good works.
“Faith by itself, if it is not accompanied by action, is dead.”
James 2:17, NIV
Catholic and Orthodox Christians likewise reject the idea that salvation can be earned apart from grace.
They place greater emphasis on the believer’s cooperation with grace in the life of salvation.
The real debate is not whether Christians should obey God. All three say yes. The debate is how obedience relates to justification and salvation.
How Does God Give Grace to His People?
Sacraments are another major dividing point.
Baptism, Confirmation, Eucharist, Penance, Anointing of the Sick, Holy Orders, and Matrimony.
Orthodoxy commonly speaks of seven principal mysteries, while viewing the whole life of the church sacramentally.
Most Protestants recognize Baptism and the Lord’s Supper because these were directly instituted by Christ.
What Happens to the Bread and Wine?
Christians have disagreed sharply here.
The substance of bread and wine becomes Christ’s body and blood while the outward appearances remain.
Orthodoxy strongly affirms that the bread and wine truly become Christ’s body and blood while avoiding overly precise philosophical explanation.
Lutherans affirm a strong real presence, Reformed Christians emphasize spiritual participation, while many Baptists and evangelicals emphasize memorial.
“Do this in remembrance of me.”
Luke 22:19, NIV
Another Place of Agreement—and Disagreement
Catholics and Orthodox Christians baptize infants as well as adult converts.
Many Protestants do the same, including Lutherans, Anglicans, Methodists, and Presbyterians.
Baptists and many evangelical churches practice believer’s baptism, baptizing those who personally profess faith.
There are also differences over what baptism accomplishes.
Catholics and Orthodox Christians generally speak more strongly about baptism’s role in regeneration and entry into the life of the church.
Protestants range from similarly strong sacramental views to views emphasizing baptism primarily as a sign and public confession of faith.
Why Do Catholics and Orthodox Christians Give Mary So Much Attention?
All historic Christians affirm that Mary was the mother of Jesus and should be honored as a faithful servant of God.
The early church also called her Theotokos—“God-bearer” or “Mother of God”— not to make Mary divine, but to defend the truth that the child she bore was truly God incarnate.
Catholics and Orthodox Christians give Mary a much more prominent devotional role than most Protestants.
Roman Catholicism also teaches doctrines such as the Immaculate Conception and Assumption of Mary.
Orthodoxy deeply venerates Mary but does not define every Marian doctrine in precisely the same way as Rome.
Protestants usually honor Mary as blessed among women while rejecting devotional practices they believe lack sufficient biblical foundation.
“From now on all generations will call me blessed.”
Luke 1:48, NIV
Should Christians Ask Departed Saints to Pray for Them?
Catholic and Orthodox Christians distinguish between worship, which belongs to God alone, and veneration or honor given to saints.
They believe Christians in heaven remain alive in Christ and can pray for believers on earth.
Protestants generally reject invoking departed saints.
They emphasize direct access to God through Christ.
“There is one God and one mediator between God and mankind, the man Christ Jesus.”
1 Timothy 2:5, NIV
The disagreement is not over whether Christians should pray for one another. It is whether Scripture supports asking believers who have died to intercede for us.
The Pope Is One of the Largest Dividing Lines
Roman Catholicism teaches that the pope, as bishop of Rome and successor to Peter, holds a unique pastoral authority in the universal church.
Under defined circumstances, Catholic teaching also holds that the pope can teach infallibly on matters of faith and morals.
Eastern Orthodoxy rejects universal papal jurisdiction.
Orthodox bishops are understood as fundamentally equal, though some sees have greater historic honor.
Protestantism rejects the papacy as a divinely instituted universal office.
The question is not whether the church needs leadership. It is what kind of authority Christ actually gave to church leaders.
Three Different Leadership Structures
Pope, bishops, priests, and deacons, with a clearly defined universal structure.
Bishops govern regional churches in communion with one another without one universal bishop holding papal authority.
Episcopal, presbyterian, congregational, elder-led, and other forms exist.
What Does It Mean to Continue the Apostolic Church?
Catholics and Orthodox Christians emphasize apostolic succession through bishops whose ordination is traced historically through previous bishops.
Many Anglicans also claim historic episcopal succession.
Most other Protestants emphasize succession of teaching rather than an unbroken line of ordination.
From that Protestant perspective, a church is apostolic when it faithfully teaches the doctrine of the apostles.
“They devoted themselves to the apostles’ teaching.”
Acts 2:42, NIV
What Happens After Death?
Roman Catholicism teaches purgatory as a final purification for those who die in God’s grace but still require cleansing before entering the fullness of heaven.
Purgatory is not understood as a second opportunity for unbelievers to be saved.
Eastern Orthodoxy prays for the departed but generally does not accept the Roman Catholic formulation of purgatory.
Protestants generally reject purgatory, emphasizing the sufficiency of Christ’s righteousness and the believer’s entrance into God’s presence after death.
“Today you will be with me in paradise.”
Luke 23:43, NIV
Orthodoxy Often Describes Salvation as Becoming Like God
This phrase can sound alarming if misunderstood.
Orthodoxy does not teach that human beings become God by nature.
Theosis refers to participation in God’s life by grace.
“You may participate in the divine nature.”
2 Peter 1:4, NIV
The emphasis is on transformation.
Healing.
Holiness.
Communion with God.
Protestants also teach growing conformity to Christ, usually using terms such as sanctification and glorification.
Why Confess Sins to a Priest?
Catholic and Orthodox Christians practice sacramental confession before a priest.
The priest does not replace God.
Rather, he acts ministerially in declaring forgiveness and guiding the penitent.
Protestants generally emphasize direct confession to God.
“If we confess our sins, he is faithful and just and will forgive us our sins.”
1 John 1:9, NIV
Protestants also recognize the biblical value of confessing sins to other believers.
“Confess your sins to each other and pray for each other.”
James 5:16, NIV
The Three Traditions Can Feel Very Different on Sunday
Liturgical worship centered on the Mass and especially the Eucharist.
Highly liturgical and sensory worship using icons, incense, chanting, ancient prayers, and the Eucharist.
Worship varies greatly, but preaching of Scripture normally occupies a central position.
The differences in worship reveal deeper differences in how each tradition understands the church, sacraments, authority, and God’s presence.
Why Are Orthodox Churches Filled With Icons?
Orthodox Christians distinguish between worshiping God and venerating sacred images.
Icons are understood as witnesses to the Incarnation and reminders of the communion of saints.
Catholics also use religious images and statues extensively.
Protestant views vary.
Lutherans and Anglicans commonly use Christian art.
Reformed traditions historically have been more cautious, especially concerning images used devotionally.
They Do Not All Use Exactly the Same Old Testament Canon
All three share the same 27-book New Testament.
But their Old Testament collections differ.
The differences concern books sometimes called the Apocrypha or Deuterocanonical books.
Protestants regard them as valuable historical writings but not canonical Scripture.
Protestantism Was Not Simply a Disagreement About Church Style
The Reformers believed serious doctrinal issues were at stake.
Among them:
The Reformation was fundamentally a debate about the Gospel and the authority by which the church knows and proclaims that Gospel.
“Protestant” Covers a Very Wide Range of Churches
Protestantism is not one denomination.
It includes:
These groups disagree among themselves about baptism, Communion, predestination, spiritual gifts, church government, and other questions.
So statements about “what Protestants believe” should usually be understood as broad historical patterns, not universal descriptions of every Protestant church.
A Simple Comparison
| Question | Roman Catholic | Eastern Orthodox | Protestant |
|---|---|---|---|
| Final authority | Scripture, Tradition, Magisterium | Scripture within Holy Tradition | Scripture as final authority |
| Universal pope | Yes | No | No |
| Sacraments | Seven | Usually seven principal mysteries | Usually two |
| Infant baptism | Yes | Yes | Some yes, some no |
| Real presence in Eucharist | Yes | Yes | Views differ |
| Invocation of saints | Yes | Yes | Generally no |
| Marian devotion | Strong | Strong | Generally limited |
| Purgatory | Yes | Not in Roman form | No |
| Justification by faith alone | No, not in Protestant sense | Generally not framed that way | Historic Protestant doctrine |
Yes and No
At the broadest level, all three stand within historic Christianity.
They confess the Trinity.
Christ’s divinity.
His death and resurrection.
Yet their differences are not merely decorative.
Authority matters.
The definition of justification matters.
The role of the church matters.
The nature of the sacraments matters.
The role of Mary and the saints matters.
We should not exaggerate the differences, but neither should we pretend they are unimportant.
Accuracy and Charity Belong Together
It is easy to criticize a distorted version of someone else’s beliefs.
Protestants sometimes describe Catholic teaching in ways Catholics themselves would reject.
Catholics sometimes describe Protestantism as though all Protestants were anti-sacramental individualists with no regard for church history.
Orthodox Christians can sometimes speak as though everyone outside Orthodoxy simply abandoned the ancient church.
None of those caricatures helps.
“Speaking the truth in love.”
Ephesians 4:15, NIV
Christian disagreement should be honest enough to name real differences and charitable enough to describe the other side fairly.
Go Back to Scripture
Church history matters.
Tradition matters.
Creeds matter.
Great theologians matter.
But every Christian eventually has to ask:
Tradition can help us read Scripture. It should never become an excuse not to examine Scripture.
Do Not Lose Jesus in the Debate About Christianity
It is possible to know everything about denominations and still miss the center of the Christian faith.
Christianity is not finally about:
Rome.
Constantinople.
Wittenberg.
Geneva.
Canterbury.
Or any other earthly center.
It is about Jesus Christ.
“Salvation is found in no one else.”
Acts 4:12, NIV
Churches matter because Christ matters. Doctrine matters because Christ matters. Scripture matters because it brings us to Christ.
When Comparing Christian Traditions
Roman Catholic, Orthodox, and Protestant
These are not three completely unrelated religions.
Nor are they simply three identical expressions of Christianity with different worship styles.
They share ancient Christian foundations.
They also disagree about important questions.
Roman Catholicism emphasizes the authority of Scripture, Tradition, and the teaching church.
Eastern Orthodoxy emphasizes continuity with the worship, councils, and tradition of the ancient church.
Protestantism emphasizes the final authority of Scripture and justification by grace through faith because of Christ.
Those differences deserve careful study.
But the study should never become merely a contest over which label wins.
“What about you?” he asked. “Who do you say I am?”
Matthew 16:15, NIV
Read Scripture.
Learn the history.
Understand the differences.
Treat people fairly.
Test every doctrine carefully.
And keep coming back to Jesus.