Growing tensions between East and West

The cracks and fissures in Christian unity which led to the Great Schism started to become evident as early as the fourth century. Although 1054 is the date usually given for the beginning of the Great Schism, there is, in fact, no specific date on which the schism occurred. What really happened was a complex chain of events whose climax culminated with the sacking of Constantinople by the Fourth Crusade in 1204. 
The events leading to schism were not exclusively theological in nature. Cultural, political, and linguistic differences were often mixed with the theological. Any narrative of the schism which emphasises one at the expense of the other will be fragmentary. Unlike the Copts or Armenians who broke from the Church in the fifth century, the eastern and western parts of the Church remained loyal to the faith, from their perspective, and to the authority of the seven ecumenical councils. They were united, by virtue of their common faith and tradition, in one Church. 
Nonetheless, the transfer of the Roman capital to Constantinople inevitably brought mistrust, rivalry, and even jealousy to the relations of the two great sees, Rome and Constantinople. It was easy for Rome to be jealous of Constantinople at a time when it was rapidly losing its political prominence. In fact, Rome refused to recognise the conciliar legislation which promoted Constantinople to second rank. But the estrangement was also helped along by the German invasions in the West, which effectively weakened contacts. The rise of Islam with its conquest of most of the Mediterranean coastline (not to mention the arrival of the pagan Slavs in the Balkans at the same time) further intensified this separation by driving a physical wedge between the two worlds. The once homogenous unified world of the Mediterranean was fast vanishing. Communication between the Greek East and the Latin West by the 600s had become dangerous and practically ceased.The Great Schism: The Estrangement of Eastern and Western Christendom
Two basic problems — the primacy of the bishop of Rome and the procession of the Holy Spirit — were involved. These doctrinal novelties were first openly discussed in Photius's patriarchate. 
By the fifth century, Christendom was divided into a pentarchy of five sees with Rome holding the primacy. This was determined by canonical decision and did not entail hegemony of any one local church or patriarchate over the others. However, Rome began to interpret her primacy in terms of sovereignty, as a God-given right involving universal jurisdiction in the Church. The collegial and conciliar nature of the Church, in effect, was gradually abandoned in favour of supremacy of unlimited papal power over the entire Church. These ideas were finally given systematic expression in the West during the Gregorian Reform movement of the eleventh century. The Eastern churches viewed Rome's understanding of the nature of episcopal power as being in direct opposition to the Church's essentially conciliar structure and thus saw the two ecclesiologies as mutually antithetical.
This fundamental difference in ecclesiology would cause all attempts to heal the schism and bridge the divisions to fail. Rome based her claims to "true and proper jurisdiction" (as the Vatican Council of 1870 put it) on St. Peter. This "Roman" exegesis of Mathew 16:18, however, was unacceptable to the patriarchs of Eastern Orthodoxy. For them, specifically, St. Peter's primacy could never be the exclusive prerogative of any one bishop. All bishops must, like St. Peter, confess Jesus as the Christ and, as such, all are St. Peter's successors. The churches of the East gave the Roman See, primacy but not supremacy. The Pope being the first among equals, but not infallible and not with absolute authority.The Orthodox Church London by Ware, Kallistos St. Vladimir's Seminary Press 1995 ISBN 978-0913836583
The other major irritant to Eastern Orthodoxy was the Western interpretation of the procession of the Holy Spirit. Like the primacy, this too developed gradually and entered the Creed in the West almost unnoticed. This theologically complex issue involved the addition by the West of the Latin phrase filioque ("and from the Son") to the Creed. The original Creed sanctioned by the councils and still used today by the Orthodox Church did not contain this phrase; the text simply states "the Holy Spirit, the Lord and Giver of Life, who proceeds from the Father." Theologically, the Latin interpolation was unacceptable to Eastern Orthodoxy since it implied that the Spirit now had two sources of origin and procession, the Father and the Son, rather than the Father alone.The Mystical Theology of the Eastern Church by Vladimir Lossky, SVS Press, 1997. (ISBN 0–913836–31–1) James Clarke & Co Ltd, 1991. (ISBN 0–227–67919–9) In short, the balance between the three persons of the Trinity was altered and the understanding of the Trinity and God confused. The result, the Orthodox Church believed, then and now, was theologically indefensible. But in addition to the dogmatic issue raised by the filioque, the Byzantines argued that the phrase had been added unilaterally and, therefore, illegitimately, since the East had never been consulted.History of Russian Philosophy by Nikolai Lossky ISBN 978-0823680740 Quoting Aleksey Khomyakov pg 87 The legal formalism and logical rationalism of the Roman Catholic Church have their roots in the Roman State. These features developed in it more strongly than ever when the Western Church without consent of the Eastern introduced into the Nicene Creed the filioque clause. Such arbitrary change of the creed is an expression of pride and lack of love for one's brethren in the faith. "In order not to be regarded as a schism by the Church, Romanism was forced to ascribe to the bishop of Rome absolute infallibility." In this way Catholicism broke away from the Church as a whole and became an organisation based upon external authority. Its unity is similar to the unity of the state: it is not necessarily rational but is rationalistic and legally formal. Rationalism has led to the doctrine of the works of supererogation, established a balance of duties and merits between God and man, weighing in the scales sins and prayers, trespasses and deeds of expiation; it adopted the idea of transferring one person's debts or credits to another and legalised the exchange of assumed merits; in short, it introduced into the sanctuary of faith the mechanism of a banking house. In the final analysis, only another ecumenical council could introduce such an alteration. Indeed the councils, which drew up the original Creed, had expressly forbidden any subtraction or addition to the text.
category:Christianity