1054 The East-West Schism

From Christian History:

[...]In 1048 a French bishop was elected as Pope Leo IX. He and the clerics who accompanied him to Rome were intent on reforming the papacy and the entire church. Five years earlier in Constantinople, the rigid and ambitious Michael Cerularius was named patriarch.

Problems arose in Southern Italy (then under Byzantine rule) in the 1040s, when Norman warriors conquered the region and replaced Greek [Eastern] bishops with Latin [Western] ones. People were confused, and they argued about the proper form of the liturgy and other external matters. Differences over clerical marriage, the bread used for the Eucharist, days of fasting, and other usages assumed an unprecedented importance.

When Cerularius heard that the Normans were forbidding Greek customs in Southern Italy, he retaliated, in 1052, by closing the Latin churches in Constantinople. He then induced bishop Leo of Ochrid to compose an attack on the Latin use of unleavened bread and other practices. In response to this provocative treatise, Pope Leo sent his chief adviser, Humbert, a tactless and narrow-minded man with a strong sense of papal authority, to Constantinople to deal with the problem directly.

On arriving in the imperial city in April 1054, Humbert launched into a vicious criticism of Cerularius and his supporters. But the patriarch ignored the papal legate, and an angry Humbert stalked into Hagia Sophia and placed on the altar the bull of excommunication. He returned to Rome convinced he had gained a victory for the Holy See.

Dramatic though they were, the events of 1054 were not recorded by the chroniclers of the time and were quickly forgotten. Negotiations between the pope and the Byzantine emperor continued, especially in the last two decades of the century, as the Byzantines sought aid against the invading Turks. In 1095, to provide such help, Pope Urban II proclaimed the Crusades; certainly there was no schism between the churches at that time. Despite episodes of tension and conflict, Eastern and Western Christians lived and worshiped together.

In the latter half of the twelfth century, however, friction between the groups increased, caused not so much by religious differences as by political and cultural ones. Violent anti-Latin riots erupted in Constantinople in 1182, and in 1204 Western knights brutally ravaged Constantinople itself. The tension accelerated, and by 1234, when Greek and Latin churchmen met to discuss their differences, it was obvious they represented different churches.

Underlying Causes of the Break
What caused the schism? It was not the excommunications of 1054; not differences in theology, discipline, or liturgy; not political or military conflicts. These may have disposed the churches to draw apart, as did prejudice, misunderstanding, arrogance, and plain stupidity. More fundamental, perhaps, was the way each church came to perceive itself.

The eleventh-century reform in the Western Church called for the strengthening of papal authority, which caused the church to become more autocratic and centralized. Basing his claims on his succession from St. Peter, the pope asserted his direct jurisdiction over the entire church, East as well as West.

The Byzantines, on the other hand, viewed their church in the context of the imperial system; their sources of law and unity were the ecumenical councils and the emperor, whom God had placed over all things, spiritual and temporal. They believed that the Eastern churches had always enjoyed autonomy of governance, and they rejected papal claims to absolute rule. But neither side was really listening to the other. [...]