Religious Successors of Rome

For centuries, the Roman Empire dominated the Mediterranean Sea, which they called “mare nostrum” or “our sea.” People of the time likely believed the huge empire would last forever. No one expected it would split into parts divided by politics and religion, but over time the empire became unstable.

The Roman empire split by the fifth century CE. Following the empire’s decline, three main successors emerged in the region. Each of these societies eventually would take Rome’s place by restoring political and social order in new ways. They based their communities largely on religion. One successor was Islam, whose followers established a caliphate that later conquered a large portion of formerly Roman territory. The other two were the Byzantine Empire (or Byzantine Christendom) in the east and many states practicing Roman Catholicism in the west (or Latin Christendom).

The communities of Byzantium and Latin Christendom shared a common bond of Christian faith. Sometimes, we collectively call them “Christendom.” The communities of Western Europe in this period are generally known as Latin Christendom, while the eastern region of Europe formed a Christian state around the city of Byzantium (Constantinople). It was similar enough to the Roman Empire that people living under Byzantine rule would have proudly called themselves Romans. The Christian faith became a network that linked the entire region. People could travel and trade across this vast region, even though they may not have spoken the same language.

Yet, although Latin Christendom and the Empire of Byzantium shared one Christian faith, they developed different traditions. These traditions become part of their faith and shaped their communities in different ways.

Byzantium and the beginnings of religious schism

Unlike Latin Christendom, Byzantium remained one unified empire during most of this period. One of the most important early rulers of Byzantium was Justinian, who ruled from 527 to 565 CE. Justinian was born to peasant parents but became emperor with the help of his uncle. Justinian’s wife, Theodora, was his most important advisor and together they made sure the emperor was at the center of both state and religious developments. He wanted the emperor to control all aspects of the state and the church.

As time went on, religious differences emerged between the Byzantine practice of Christianity and that of Latin Christendom. One of the most important disputes revolved around the divine nature of Jesus. The eastern church believed that Jesus was the son of God and therefore of two natures—one divine and one human. The western church believed that Jesus was the son of God, but that both had existed for all of eternity and had a divine nature. Justinian called a council of church leaders together to resolve these differences but neither side was willing to budge. There were also divisions based on language, with eastern Christians speaking Greek and western Christians speaking Latin. Eastern Christendom permitted married priests, while Latin Christian priests were celibate. The two churches also used different types of bread for the Eucharist.

In the eighth century, there was a dispute about icons, or artistic images of Christ, Mary, and the saints. This division became known as the iconoclasm controversy. In Byzantium, the emperor Leo III, who ruled from 717 to 741 CE, banned imagery depicting Christ or Mary. For a community bound by their religious faith, these images meant everything. It wasn’t like you could scroll back on your social media feed to remember what something looked like. At a time when many were not literate, these icons represented links to the divine and a tool to understand Biblical stories. The icons allowed people from all social classes to understand and participate in the faith, which helped to create a sense of community among believers. The ban was eventually lifted but not until the mid-ninth century. By that time iconoclasm had created even more tension between the two churches of the east and west.

Latin Christendom as a new community

In the eighth century, or around 700 CE, a new warrior dynasty arose. The dynasty would nearly re-create the entire old Roman empire in Western Europe. The new ruling family, the Carolingians, were a mix of Germanic culture and Christian faith. Unlike the Byzantine empire, the Christian rulers in Western Europe did not control religious doctrine. That was the pope’s job. On Christmas Day in the year 800 CE, Pope Leo III crowned the Carolingian ruler Charlemagne “emperor of the Romans.” This affirmed papal authority to crown emperors and declared a firm separation from Byzantine control. Between the crowning of Charlemagne and the iconoclasm controversy, tensions between the west and east were nearing a breaking point.

By the eleventh century, Latin Christendom was experiencing a new wave of religious enthusiasm. Churches sprang up across the medieval landscape. People would travel great distances to visit shrines dedicated to Christian saints, driven by a quest for personal salvation.

Yet this religious passion endangered religious minority groups. Bursts of anti-Semitic violence threatened Jewish groups. What began as peaceful pilgrimages would eventually evolve into armed crusades against the so-called “enemies of Christ.” These enemies often included Jews, Muslims, and even members of the Byzantine church. These crusades united the communities of Latin Christendom against what was perceived as a common enemy. The goal was to reclaim the Holy Land (Jerusalem) from Muslim rule. However, the crusaders often persecuted Jews and other minority groups as well.

The Byzantium and Latin Christendom network splits

By the eleventh century, Byzantine and Latin forms of Christianity were quite different. Both sides wanted to prevent what they believed to be the incorrect or heretical doctrine of the other form from spreading. The pope began closing churches in Italy that were aligned with the eastern faith. The Byzantine patriarch responded by closing Latin churches in the empire. Eventually, the pope decided to excommunicate the patriarch from the church and the patriarch did the same to the pope.

In 1054 CE, the two churches officially broke apart in what is known as the Great Schism. Now there were two Christian faiths: Roman Catholicism and Eastern Orthodoxy. However, the break was not entirely complete. Nearly 40 years after the official schism, the Byzantine empire would request the Catholic Church’s help in defeating Muslims, who were threatening to invade Constantinople.

The Crusades were actively promoted by both popes and patriarchs, emperors and kings. These holy wars dominated much of the twelfth and thirteenth centuries. Thousands of ordinary people from all over Latin Christendom walked over 2,000 miles through Europe and the Byzantine empire to reach the Holy Land, while others traveled overseas. They were driven by religious enthusiasm and the promise of new land. This campaign was remarkably successful in uniting Latin Christendom and even mending the division between eastern and western Christianity for a time. Yet the truce didn’t last long. During the fourth Crusade, Latin crusaders sacked the Eastern Orthodox city of Constantinople.