What Is the Filioque, and Why Did It Divide East and West?

One Word

Every Sunday, Latin Catholics profess in the Nicene Creed that the Holy Spirit “proceeds from the Father and the Son.” In Latin, “and the Son” is a single word: filioque.

The Orthodox Churches recite the same Creed without it. For them, the Spirit “proceeds from the Father.” This difference, over one word, became one of the major causes of the division between the Catholic and Orthodox Churches. It is still discussed between them today.

To understand why such a small word matters so much, we need both history and theology.

The Original Creed

The Creed most Christians recite at Sunday worship is the Nicene-Constantinopolitan Creed. It was formulated by the Council of Nicaea in 325 and expanded by the Council of Constantinople in 381, which added a fuller statement about the Holy Spirit: “who proceeds from the Father, who with the Father and the Son is adored and glorified.”

The phrase “proceeds from the Father” echoes Jesus’ words: “the Spirit of truth, who proceeds from the Father” (John 15:26). The Council of Ephesus in 431 forbade anyone to compose a different creed, which later became an important argument in the debate.

How the Word Was Added

The filioque appeared first in Spain. The Third Council of Toledo, in 589, used it as part of the Visigoths’ conversion from Arianism, the heresy that denied the full divinity of the Son. Stressing that the Spirit proceeds from the Son as well as the Father underlined that the Son is fully equal to the Father.

The addition spread through the Frankish lands. Charlemagne’s court promoted it and accused the Greeks of error for omitting it.

Rome was cautious. Pope Leo III, around 809, agreed with the theology of the filioque but refused to add it to the Creed. He is said to have had the original Creed, without the word, engraved on silver shields in Greek and Latin and displayed in St Peter’s.

Rome finally adopted the filioque in the Creed in the early eleventh century. It is traditionally dated to 1014, when the Creed was sung at the coronation of the Emperor Henry II.

Why the East Objected

Eastern Christians raised two objections.

The procedural objection. The Creed belonged to the whole Church, agreed by ecumenical councils. The West had altered it unilaterally, without an ecumenical council. To many in the East, this was an abuse of authority.

The theological objection. In the ninth century, Patriarch Photius of Constantinople argued that the filioque undermined the monarchy of the Father: the principle that the Father is the sole source of divinity within the Trinity. If the Spirit proceeds from the Father and the Son, he argued, it seems there are two sources of the Spirit, or that the Father and Son are merged into one.

The issue became tangled with disputes over papal authority, and it was among the grievances in the mutual excommunications of 1054.

The Western Theology

What did the West mean by the filioque? The theology goes back to St Augustine and St Ambrose, and earlier.

The Persons of the Trinity are distinguished only by their relations of origin. The Father begets the Son; the Son is begotten; the Spirit proceeds. If the Spirit were not related to the Son by origin, Western theologians argued, there would be nothing to distinguish them as Persons.

Crucially, the Western tradition never taught two sources of the Spirit. The Second Council of Lyons (1274) defined that the Spirit proceeds from the Father and the Son “not as from two principles, but as from one principle; not by two spirations, but by one single spiration.” The Father remains the ultimate source: He gives the Son everything He has, including being the source of the Spirit with Him.

The Catechism explains that the Latin tradition, in confessing that the Spirit proceeds from the Father and the Son, says the Father, as “the principle without principle,” is the first origin of the Spirit, and as Father of the only Son, is with the Son the single principle from which the Spirit proceeds (CCC 248).

Through the Son

Many Greek Fathers, such as St Maximus the Confessor and St John Damascene, spoke of the Spirit proceeding from the Father through the Son. This expresses the same order within the Trinity in a way more natural to Eastern theology.

At the Council of Florence (1439), Greek and Latin bishops agreed that the two formulas, “from the Father and the Son” and “from the Father through the Son,” express the same faith when rightly understood. The union reached there did not hold. But the theological agreement remains important.

The Catechism affirms that the two traditions are legitimately complementary, provided neither becomes rigid (CCC 248).

Where Things Stand Today

Relations between Catholics and Orthodox have improved greatly since the 1960s, and the filioque is now discussed in a calmer spirit.

In 1995, the Pontifical Council for Promoting Christian Unity published a clarification, The Greek and Latin Traditions regarding the Procession of the Holy Spirit. It acknowledged that the Father is the sole source of the Trinity and that the Greek word for “proceeds” in the Creed refers to the Spirit’s origin from the Father alone. It explained the Latin word as expressing something slightly different: the communication of divinity from the Father through the Son.

In practice, Eastern Catholic Churches in full communion with Rome usually recite the Creed without the filioque. On several occasions, popes have recited the Creed in Greek without it, alongside Orthodox patriarchs.

The theological question is not fully resolved, but most theologians on both sides now see it as a difference of emphasis rather than of faith. The deeper issues dividing Catholics and Orthodox are now generally recognised to concern the authority of the Pope.

Why It Matters

To many people, a dispute over one word about the inner life of God seems absurdly abstract. But for Christians, the Trinity is not an abstraction. It is the God we worship, in whose name we are baptised, and whose life we are called to share.

The filioque debate shows how seriously the Church has always taken the truth about God. It also shows that a long and bitter quarrel can, with patience and charity, be reconsidered in a spirit of brotherhood.