Filioque Controversy

The words and the Son, added in the Latin West to the Creed’s statement that the Holy Spirit proceeds from the Father. They appear first in Spain, at Toledo in 589, and spread through the Frankish church; Charlemagne’s theologians pressed for them, and Pope Leo III refused and had the Creed engraved without them on silver shields in St Peter’s. Rome itself began singing them only around 1014. The Orthodox objection is double. On the canonical side, the Creed of an Ecumenical Council was changed by one part of the Church alone, when Ephesus had forbidden any other creed. On the theological side, making the Son a second source of the Spirit undoes the monarchy of the Father and blurs the Persons into their shared essence. St Photius, the council of 879-880 and St Mark of Ephesus each held the line, and it remains one of the questions between the churches.