Filioque

===First Eastern opposition===
[[File:Maximus Confessor.jpg|thumb|Maximus the Confessor]]
The first recorded objection by a representative of Eastern Christianity against the Western belief that the Holy Spirit proceeds from the Father and the Son occurred when [[Patriarch Paul II of Constantinople]] ({{Reign|642|653|lk=abbr}}) made accusations against either [[Pope Theodore I]] ({{Reign|642|649|lk=abbr}}) or [[Pope Martin I]] ({{Reign|649|653|lk=abbr}}) for using the expression.{{sfn|Bulgakov|2004|pp=91–92}} Theodore I excommunicated Paul II in 647 for [[Monothelitism]].{{sfn|Norwich|1997|p=99}} In response to the attack by Paul, Maximus the Confessor, a Greek opponent of Monothelitism, declared that it was wrong to condemn the Roman use of "and the Son" because the Romans "have produced the unanimous evidence of the Latin Fathers, and also of [[Cyril of Alexandria]] [...] On the basis of these texts, they have shown that they have not made the Son the cause of the Spirit – they know in fact that the Father is the only cause of the Son and the Spirit, the one by begetting and the other by procession – but that they have manifested the procession through him and have thus shown the unity and identity of the essence." He also indicated that the differences between the Latin and Greek languages were an obstacle to mutual understanding, since "they cannot reproduce their idea in a language and in words that are foreign to them as they can in their mother-tongue, just as we too cannot do".{{refn|Maximus the Confessor, ''[http://www.monachos.net/content/patristics/patristictexts/185-maximus-to-marinus Letter to Marinus]'', (PG 91:136).}}