Educational Travel Lesson Plans

Byzantine Istanbul (330-1453): Great Schism of 1054: Orthodox Christianity



Through the investigation of selected sources, students in this lesson will identify, understand and be able to explain in detail the Great Schism of 1054 that split the Christian Church into Eastern Orthodoxy and Roman Catholicism, what different theological and political issues caused the rift, and what attempts have been made to reconcile those differences.


World History

Grade Level



90 minutes

Tour Links

  • St. Peter’s Basilica, Vatican
  • Hagia Sophia, Istanbul
  • Church of St. George, Istanbul

Essential Questions

  • How did the Patriarch of Constantinople (Istanbul) come to prominence in the early Christian Church?
  • Why did Christianity split into Roman Catholic and Eastern Orthodox churches in 1054?
  • What were the issues that precipitated the Great Schism?  What were the major theological differences?  What were the major political differences?
  • How have relations been between the Pope and the Patriarch since the Great Schism of 1054?  Is there a possibility of reconciliation?

Key Terms

  • Apostolic
  • Byzantine Empire
  • Byzantium
  • Constantinople
  • Ecumenical
  • Great Schism of 1054
  • Hagia Sophia
  • Ottoman Empire
  • Papacy
  • Patriarch
  • Primacy

Its tradition stretches back to the days of the earliest church fathers, linked to such untouchable Christian heavy-weights as St. Paul, the apostle St. Andrew and St. John the Divine.  Its land is littered with ancient Christian ruins from such sites as Ephesus, Galatia, Corinth and Nicaea.  In the early days of the church, it was the center of the Christian community.  By the fourth century CE, as the new religion was establishing itself as the official religion in the Roman Empire, its bishop enjoyed a status equal to the Bishop of Rome.  Its grand cathedral was the largest in Christendom for over 1000 years.  Today, in a land where over 99% of the population is Muslim, there is little left to remind visitors of its former grandeur.  That land is Turkey.

In ancient times, Anatolia (as Turkey was known during its Roman Age) was a land of Greeks, many of whom were much more educated than people in other parts of the Empire.  Most of the early church fathers spoke Greek, the common lingua franca of the Eastern Roman Empire.  Their earliest writings, including much of what is now found in the Canonical Bible, were written in Greek and intended for Greek audiences.  While there is no doubt that the modern Christian community worldwide looks to Jerusalem as its holiest city, a careful examination will reveal that the once fledgling religion really took hold in Anatolia.  St. Paul himself is said to have established churches in Anatolia and Thrace (on the European side of the Bosporus across from modern Turkey), and many of the saint’s famous letters now found in the New Testament were written back to those communities.  As the church expanded across the Mediterranean, Byzantium (today’s modern Istanbul) was recognized as one of the five Apostolic Sees of Christianity, a designation reflecting its link to an original apostle, equal and on par with Rome, Alexandria (Egypt), Antioch (in southern Turkey on the border with modern Syria), and Jerusalem.  Even as the papacy in Italy began to assert control over Christendom after it was legalized in the empire, the Fourth Ecumenical Council in 451 CE made the Bishop of Constantinople (as the city was now called) equal in rank to the Bishop of Rome. 

As Western Europe fell into the Dark Ages during the Germanic invasions, contact between the eastern and western halves of the empire grew strained and sporadic.  The two Christian sections grew very differently.  In Rome, the Pope reigned as the unquestioned religious head over a land with little political stability or unity.  Once pagan Germanic tribes like the Franks, Anglo-Saxons and Goths took over former Roman provinces and quickly accepted the Christian faith, giving the papacy in Rome immense power, a dominance that only grew as time went on.  During the Middle Ages, the church expanded on the idea that salvation outside the church’s body was impossible (an early church teaching), and by the end of the first millennium CE, the Pope even had power and sway over the monarchs of medieval Europe.  The threat of excommunication, literally throwing someone out of the church and thus denying that person entrance to the gates of heaven, was usually enough to keep all but the most radical dissidents in line.  Those not so frightened by excommunication could be silenced by execution.

In the eastern Mediterranean, however, things were very different.  Constantinople was still the capital of the Byzantine Empire (as the Eastern Roman Empire became known after the West fell).  It was a city of culture and learning, led by powerful emperors and patriarchs.  Constantine the Great, in calling the Council of Nicaea in 325 CE, had interjected the imperial government into church affairs, a tradition that continued throughout the history of Byzantine rule.  Over the centuries, differences in theology combined with political rivalries to drive the Christian factions further apart.

Early in the second millennium CE the crisis came to a head when the Patriarch of Constantinople refused to accept papal primacy and leadership.  In 1053 he closed all churches in Constantinople that followed the “Latin Rite” and followed the leadership of the Pope.  The Vatican struck back.  On 16 July 1054, Cardinal Humbert of Silva Candida burst into Hagia Sophia in the middle of Mass, walked up to the front of the main altar and announced to the congregation that Patriarch Michael I Cerularius, who was then saying Mass, had been excommunicated by Pope Leo IX.  In Humbert’s hand was a papal bull, an official document signed and stamped by the Pope himself that also threatened excommunication to any person who followed the patriarch and refused to submit to the primacy of the Bishop of Rome (there were theological issues as well, such as whether or not to use unleavened bread at mass).  The Patriarch in turn excommunicated the Pope and the cardinal.  The break was complete. 

Since the Great Schism of 1054, the two Christian churches have grown significantly in their own ways.  Over the centuries, there have been attempts on both sides to arrive at some sort of reconciliation, each of which has found varying degrees of success, but in the end many of the political and theological issues that separated Rome and Constantinople a millennium ago still remain.  Orthodox Christians still refuse to accept the Roman Pope as their spiritual leader.  Issues over icons and unleavened bread have ingrained themselves into doctrine.

In 1967, after the Second Vatican Council acknowledged that the Catholic Church might have been wrong in some of its positions in 1054, Pope Paul VI visited the Patriarch in Istanbul.  Pope John Paul II visited again in 1979.  In 2006, Pope Benedict XVI visited Istanbul and participated in services on the feast day of St. Andrew.  In March 2013, Patriarch Bartholomew I flew to Rome and was present at the inaugural mass for newly elected Pope Francis, marking the first time a Patriarch of Constantinople had attended such an inauguration since the Great Schism of 1054.  Pope Francis has been invited by the Patriarch to visit Constantinople in 2014.  Perhaps closer ties between the two old Christian churches are possible as the world moves through the 21st century.

Since 1453, Constantinople, now officially called “Istanbul”, has been in Muslim hands.  Christians in the ancient city still exist, but their numbers are very small.  Many Byzantine Christians abandoned the ancient city after Hagia Sophia was converted into a mosque by the Ottomans.  Other Orthodox churches were allowed, however, to remain open and a small Christian community thrived in what became a Muslim stronghold.  To solidify his position and to quell any potential issues with the remaining Christians, Sultan Mehmed II appointed a new Patriarch in 1454 and declared him as the leader of all Christians living in the Ottoman Empire.  The Ecumenical Patriarchate of Constantinople is still headed by the Archbishop of Constantinople and his church still serves as the mother church and is generally considered to be the spiritual leader for all Orthodox churches and Orthodox Christians, both in Eastern Europe and around the world.

Through the investigation of selected sources, students in this lesson will identify, understand and be able to explain in detail the Great Schism of 1054 that split the Christian Church into Eastern Orthodoxy and Roman Catholicism, what different theological and political issues caused the rift, and what attempts have been made to reconcile those differences.

educational tour image
  1. Students will identify, understand and be able to explain in detail the Great Schism of 1054 that split the Christian Church into Eastern Orthodoxy and Roman Catholicism.
  2. Students will identify, understand and be able to explain the different theological and political issues that caused the rift in the Christian Church late in the first millennium.
  3. Students will identify, understand and be able to explain what attempts have been made in the last few years to reconcile the differences between the Eastern Orthodox and Roman Catholic churches.

To view resource web pages, download the lesson plan PDF above.

I. Anticipatory Set

  • Writing / Question: Why are there different denominations of Christianity? (5 min)
  • Handouts – Copies of documents and readings from the websites listed. (5 min)

II. Body of Lesson

  • Lecture / PPT – Great Schism of 1054 (20 min)
  • Videos – CBS & Vimeo videos on the Great Schism of 1054 (30 min)
  • Independent Activity – Students read the articles and sources on the Great Schism of 1054, taking notes as appropriate. (20 min)
  • Suggestion: All students should focus on primary sources from both sides.
  • Group Activity – Socratic Seminar: Discussion on the Great Schism of 1054. (10 min)

III. Closure

  • Assessment / DBQ – Essay: Explain in detail the Great Schism of 1054 that split the Christian Church into Eastern Orthodoxy and Roman Catholicism, what different theological and political issues caused the rift, and what attempts have been made to reconcile those differences.


On tour: Church of St. George, Istanbul

While on tour, students in Istanbul can visit the Church of St. George, where they can see for themselves the center of Orthodox Christianity.  Compared to St. Peter’s Basilica in Vatican City, the Church of St. George is very small.  Its outside façade dates from the mid-19th century, when the church was rebuilt after fire ravaged the structure.  The church has been home to the Patriarch only since 1601.  Before the Fall of Constantinople at the hands of Ottoman forces in 1453, Hagia Sophia was the Patriarch’s cathedral.  Visitors to St. George are welcome, but students should know that the site is a working church and monastery.  It has a different feel for tourists that St. Peter’s. 

On tour: Vatican City

While on tour in Rome, students will visit Vatican City, St. Peter’s Basilica and the Sistine Chapel, home not only to world famous works of art, but also to the center of the Roman Catholic Church.  Make sure to look for the Papal Balcony above the main doors at St. Peter’s Basilica.  Facing the main square, it is where the newly elected Pope traditionally addresses the crowd for the first time.  Vatican City was created in 1929 by the signing of an agreement between the Holy See and the Italian government.  Although it is the smallest country in the world, Vatican City’s independence gives the Pope a special position when dealing with heads of state from other countries.


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