Jesus prayed for the church on earth to be one (John 17), and those who recite the Nicene Creed affirm a commitment to “the one, holy, catholic, and apostolic church.” Such unity, however, often seems to escape us in practice. 

You had to see it to believe it. During the pope’s September 2010 visit to the United Kingdom, one protester’s sign stood out, far out, from the others. In large markered letters on the back of a pizza box, the theologically minded protester declared, “Drop the Filioque!”

Filioque: Why All the Fuss?

Assuming that protester was merely seeking to get noticed, the sign worked, landing him television coverage and a few interviews. But why did he oppose that phrase? And what does that phrase even mean?

The single Latin word on the sign means “and the son.” And this single Latin word holds the dubious honor of being one of the main factors responsible for the largest church split to date: the Great Schism in 1054 between the Roman Catholic Church in the West, with its seat of power in Rome, and the Orthodox Church in the East, with its seat of power in Constantinople. That’s a lot for a single word to bear.

Theologians in the West were drawn to filioque because it reflected their understanding of the Trinity. They believed the Holy Spirit proceeds from the Father and the Son. In AD 598, at the Council of Toledo, the Western church officially adopted the phrase and amended the Nicene Creed (from 325/381) accordingly. Since 598, the churches in the West have said the extra Latin word when reciting the creed. Christ’s teaching in John 16:7 offers biblical warrant for the phrase. Eastern churches, however, never appreciated that argument.

The Eastern churches, while affirming the Trinity as three persons in one substance, tend to emphasize the threeness of the Trinity, the individual persons. The West, again while affirming the orthodox definition of the Trinity, tends to emphasize the unity of the Godhead.

If we fast forward from the late 500s to the middle of the 1000s, we find that this ever-contentious phrase acutely came under the spotlight. And here’s where things get complicated, as politics (both in the empire and in the church), theology, and personalities all got jumbled together. The Western and Eastern churches were headed for a showdown.

Showdown at the Hagia Sophia

One can almost wonder how the church managed to stay together until 1054. As far back as the 300s, the Eastern and Western churches had distinct cultures and languages (Greek versus Latin), distinct liturgical or worship practices and emphases, distinct theological methods, distinct seats of power and autonomy (Constantinople versus Rome), distinct emperors, and distinct ecclesiastical leaders (the patriarch versus the pope).

These differences were pronounced and would easily flare up. Such was the case in 1054. In fact, what happened in 1054 may very well be seen as making explicit what had long been implicit.

Michael Cerularius, patriarch of Constantinople, had condemned the Western churches for the practice of using leavened bread for the Eucharist. Leo IX, the Roman pontiff from 1049–1054, dispatched emissaries to iron out the differences. These efforts at diplomacy failed miserably. The more the two sides talked, the more they disagreed. Neither side flinched, causing Leo IX’s legates to enter the Hagia Sophia (the most important church in Constantinople and seat of the Eastern patriarch) and place a papal bull of excommunication on the high altar.

Cerularius countered by convening a council of bishops that condemned Pope Leo IX and his church, too. Among the reasons was the filioque clause. The Western church, he argued, had overstepped its bounds when it amended the Nicene Creed. The Eastern church had remained pure and true. The addition of filioque became a convenient hook upon which to hang all the contention and disagreement between the churches.

So on July 16, 1054, the “one, holy, catholic, and apostolic church,” as the Nicene Creed puts it, split. And then there were two.

After 1054

Attempts were made to heal the breach, but none succeeded. When the Western church launched the Crusades, all hopes for a reunion faded. During the Fourth Crusade, in the early years of the thirteenth century, European armies sacked Constantinople, apparently distracted from their mission of securing the Holy Land. One historian of the Crusades describes the three-day siege of the city as leaving in its wake “ghastly scenes of pillage and bloodshed.” The great and ancient city of Constantinople was reduced to rubble and left in shambles.

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