Since East-West ecclesiastical relations continued, in a very damaged way because of the state of the West during the Dark Ages, the break with Rome did not occur at the time of St. Photios the Great and at the time of St. Mark Evyenios of Ephesos in 1054. It became definitive over time as the result of a number of social factors.
The differentiation of the West and beginning of its juridical orientation began with three Africans and one Milanese judge--St. Ambrose. The Punic writers--Tertullian, Cyprian, and Augustine had all been law students, lawyers, or court orators; Ambrose had been a judge. The brilliant Augustine--a passionate, convincing, and beautiful writer--developed novel doctrines of the Fall. Failing to separate what little he seemed to understand of the divine Energies from the changeless divine Essence, Augustine could hardly avoid teaching predestination . . . which in any case he needed to bolster his view of Grace--understood in volitional termsl (and will for Augustine was not uncreated Energy) in his campaign against Pelagius's teaching of salvation by good works. Augustine died over half a century before the Dark Ages had begun elsewhere; but the Vandals were at the gates of his city as he expired, and the Dark Ages began even in remote Africa--the province of Carthage (not Alexandria, which remained Greek till the Muslims conquered it).
What caused the breaking off of Rome from its Greek-language Christian roots and the New Testament energy ontology were the seven or seven and a half centuries of Dark Ages--when barbarism, 40% infant mortality, disease, life expectancy in the low thirties, and pervasive brutality and fear prevailed during a time when Rome and Ravenna, along with Milan and Trier, became villages. Rome simply lost lineal continuity with its Greek-language roots. Despite some embassies between Rome and Constantinople (mostly of a not very amiable nature) and the presence of the Byzantine Princess Theophano in the West (as the Emperor's wife, she even encouraged the Greek-speakers of Southern Italy), the prevalence of illiteracy in the West, the German emperors' zeal to declare the East heretical for their own political advantage, and the very length of the time (equivalent to the time from 1250 or 1300 to 2000) cumulatively ensured that the West would go a very separate way from the original Christian thought world of the East.
What sealed that result far more definitively was that which ended the Dark Ages: the new learning from the Semitic (Islamic and Jewish) scholarship of Córdova. This came to the West in Latin translations of Arabic translations (made in Baghdad at the end the eighth century)--translations of Greek philosophy and other scholarship--medicine, astronomy, etc. The Arabs invented algebra and chemistry; Córdova was a large, modern, and brilliant as Vyzantion or Baghdad in the latter twelfth century. The Arabic and Jewish commentaries on the Greek philosophers were of course highly juridicalized with the Shar'ia (Islamic Law) or Torah (Jewish Law). With the Lombard Gratian, ecclesiastical law became a central matter in the Christian West; nearly all of the popes from 1100 to 1300 are said to have been lawyers, and of course the Lombard Anselm (later Archbishop of Canterbury) introduced a juridicalized view of Salvation in which divine justice had to be fulfilled before God would forgive humanity's sins. With Augustine's view of inherited guilt, this constituted one of many departures from ancient Christianity that infected the West. The Lombard Peter set the scholastic tone that culminated with the Norman (Viking) Thomas Aquinas and the Scotist-Ockhamists (all Normans, though from England rather than the Kingdom of Naples like Aquinas). The Lombards and Normans as well as Burgundians (like the influential Bernard) imposed a Germanic attitude on theology in the West--then as during the Reformation and subsequently.
Luther the Ockhamist simply took what had happened a step forward and several steps backward. His two modernisms (via moderna and devotio moderna) promoted individualism and the will-based, Gnostic view of the "sacraments" that he expounded in his famous Prelude on the Babylonian captivity of the Church. Predestination was of course espoused by the Augustinian Reformers. But what became paramount and dominated Protestantism was words. The Creator had been viewed as a Word by Rome. But with the Reformers, the word preached to sinners replace sacrificial Worship offered to God: Out went the Altar, only the pulpit was left. With Calvinists, the last vestiges of the incarnational-sacramental paradigm disappeared; sacraments became virtual sermons. This took Christianity almost as far from St. Ignatios of Antioch as it might seem possible to go--but the anticredalism, individualism, and relativism of today's most active Christians has succeeded in going yet farther. The Trinity has fallen by the way to a great extent, according to research done by the Barna pollsters. An undefined Jesus saved "me" and "Jesus and I" have a personal relationship; that's about it, though a view of original guilt may endure. St. Ignatios and St. Paul's companion at Philppi, Clement, would--it seems obvious--no longer recognize it.
Church history has thus been a series of concentric circles moving ever farther from the Orthodox thought world of the early centuries. (Even the Christians in Rome spoke Greek well into the third century; even Tertullian knew Greek, though Augustine hardly knew any.) The Greek concepts of dýnamis and energy came to the West through the Arabic translations of Aristotle. If potentia more of less translated dýnamis, actus and operatio were very defective renderings of energy. What was fatal was the failure to distinguish energy from essence in the manner of the Greek Fathers. Once essence was conceptualized "energetically"--as pure existence--and both knowing and will became part of God's Essence (e.g. the divine ideas). "Energies" like willing became other than energetic in the changeless Essence. Predestination was the only logical result; it has always bugged the Western theological mind . . . that is, till anti-credalism, individualism, and relativism ousted everything traditional and resulted in Biblical translations of sarx "flesh" as "our sinful nature" and other Gnostic distortions . . . aside from the failure to understand the energy ontology of the Greek New Testament. The difference between Energizations like the Assimilation to God and Théosis and new creatings in Christ as distinct from their results--the likeness of God, new creatures in Christ, etc.--have simply gone by the board, replaced by a fanciful view of ancient Eastern Mediterranean life and the picture of Jesus as a roving, rustic, American-like preacher. With relativism thrown into the mix, one has almost reached the end of the line. . . . There is only one step to further to go. . . .