Its inclusion in the Creed is a violation of the [[canons]] of the [[Third Ecumenical Council]] in 431, which forbade and anathematized any additions to the Creed, a prohibition which was reiterated at the [[Eighth Ecumenical Council]] in 879-880. This word was not included by the [[First Ecumenical Council|Council of Nicea]] nor of [[Second Ecumenical Council|Constantinople]], and most in the [[Orthodox Church]] consider this inclusion to be a [[heresy]].
The description of the ''Filioquefilioque'' as a heresy was iterated most clearly and definitively by the great [[Church Fathers|Father ]] and [[Pillars of the Church|Pillar ]] of the Church, St. [[Photius the Great]], in his ''On the Mystagogy of the Holy Spirit''. He describes it as a heresy of [[Triadology]], striking at the very heart of what the Church believes about God.
== History ==