What are the differences between Catholic, Protestant, and Orthodox beliefs?

When people first begin exploring Christianity, one of the most common questions is: why are there so many different kinds of Christians? 

The two largest traditions within Christianity worldwide are Roman Catholicism and Protestantism. There is also a third major tradition known as Eastern Orthodoxy. Together, these three branches make up the vast majority of Christians around the world. 

So how did the differences arise, and what actually separates them today?

The East-West Schism

For the first thousand years of Christianity, the church existed as a broadly unified movement spread across the Roman Empire and beyond. However, over time, disagreements developed between the churches in the eastern and western parts of the empire.

One major disagreement was over the authority of Bishop of Rome (also known as the Pope). The Western Church believed the Pope had authority over the whole Church, while the Eastern Church saw him as an honoured leader but not the supreme authority.

Another important disagreement was about a statement added to the Nicene Creed, an early summary of Christian belief. The Western Church added the word Filioque (meaning “and the Son”), so that the creed said the Holy Spirit proceeds from the Father and the Son. 

The Eastern Church disagreed with this change. They believed the wording of such an important statement of faith should not be altered by one part of the Church without agreement from the whole Church, and they also had concerns about whether this wording accurately described the relationship between the Father, Son, and Holy Spirit. This disagreement became one of the major theological issues that contributed to the growing divide between the Eastern and Western churches.

These disagreements came to a head in 1054 when the Pope’s representatives (from the West) and the Patriarch of Constantinople (from the East) excommunicated one another, marking the formal split between what became the Roman Catholic and Eastern Orthodox churches, even though the division had been growing for many years.

Centuries later, another major division occurred within Western Christianity.

The Protestant Reformation

In the 16th century, a major movement of reform began within the Western Church. Many Christians at the time believed that some teachings and practices in the church had become unclear or had drifted away from what they believed the Bible originally taught.

This movement became known as the Reformation, and those involved were called Protestants (because they protested against Roman Catholic teaching). One of the most influential protestors was Martin Luther, a German monk and scholar.

Luther’s concerns were not about starting a new religion, but about calling the church back to what he believed was the core of the Christian faith. At the centre of his concerns was the question of how a person is made right with God. He argued, from his reading of the Bible, that people are made right with God by grace alone through faith in Jesus Christ, not by earning God’s approval through religious works. This raised questions about certain practices at the time that seemed to suggest salvation could be “helped along” through human effort or religious actions.

One issue he strongly challenged was the sale of indulgences—certificates offered by church representatives that were said to reduce punishment for sin. Luther believed this gave a misleading impression that forgiveness could be bought or earned, rather than received as a gift from God.

He also raised concerns about whether the authority for Christian belief should rest ultimately in church teaching alone, or whether it should be tested against the teaching of Scripture. Luther argued that the Bible should function as the final and decisive authority for Christian faith and practice, and that church teaching must always be measured against it.

Another area of concern was the way certain practices had developed over time within the church, including ideas about purgatory and aspects of devotional life that, in Luther’s view, did not have clear grounding in Scripture. 

These concerns led to public debate and conflict with church authorities, eventually resulting in a major division within Western Christianity. Those who aligned with Luther and similar reformers became known as Protestants, while the Roman Catholic Church continued to develop its own theological responses and reforms in the centuries that followed.

The foundation of the church

A key difference between Roman Catholics and Protestants is how they understand Jesus’ words to one his disciples, Peter, in Matthew 16:18: “You are Peter, and on this rock I will build my church.” While both Catholics and Protestants believe Jesus gives Peter a special role amongst the disciples, they largely disagree on what this actually means.

Roman Catholics see this verse as supporting the idea that Peter is the first Pope and his authority is passed down through an unbroken line of bishops of Rome.

Many Protestants (myself included) believe the “rock” is not Peter as a unique office-holder, but Peter’s confession of faith: “You are the Messiah, the Son of the living God” (Matthew 16:16). In this view, Peter is special not because he is the first pope, but because he is the one who will launch the church through his proclamation that Jesus is the Messiah.

This understanding fits with what happens after Jesus’ death and resurrection. In the book of Acts, Peter is the first apostle to publicly proclaim that Jesus is the promised Messiah (Acts 2). Around three thousand people believe the message and are baptised, marking the dramatic beginning of the Christian church. Peter is clearly the leading figure at this moment—not because he is the first Pope, Protestants would argue, but because he is the first to preach the gospel. 

Peter’s role is unique and significant, but the foundation is ultimately Christ himself and the apostolic message about him (see also Ephesians 2:20 and 1 Corinthians 3:11).

Areas of agreement

Although Protestants, Roman Catholics, and Eastern Orthodox Christians have real differences, it is important to recognise how much they also share. All three affirm: the Trinity (one God in three persons), the divinity of Jesus Christ, the death and resurrection of Jesus, and the call to follow Jesus in daily life. In other words, they share many of the central convictions of historic Christianity.

Why does this matter?

When people first discover these divisions, it can be confusing or discouraging. Some wonder whether Christianity can really be true if Christians disagree so deeply.

From a Christian perspective, disagreement is not surprising. Christians believe human beings are limited, fallible, and sometimes wrong. That means sincere Christians can still disagree on how best to interpret and apply the Bible.

Even in the New Testament, we see the early church working through significant conflicts while remaining united around the message of Jesus. For example, in Acts 15, the apostles gathered to resolve a major disagreement about whether Gentile believers needed to follow Jewish laws to become Christians. They listened, debated, and sought a decision together, while holding firmly to the truth that people are saved through the grace of Jesus.

An invitation to explore

For someone exploring Christianity today, these differences do not need to be a barrier. Instead, they can be an invitation to look more closely at the source itself: Jesus and the Bible.

Rather than beginning with church labels or traditions, it’s worth asking a simpler question: What did Jesus actually teach? What do the earliest Christian writings say? And what kind of response does Jesus himself call for?

A good place to begin is by reading one of the Gospels—such as Mark’s Gospel—and seeing what Jesus is like for yourself.