"When Charlemagne sought to revive the empire, it was merely the Latin end of the empire he revived. It was natural that a sense of rivalry between Latin Empire and Greek Empire should develop very readily. And still more readily did the rivalry of Greek-speaking Christianity and the newer Latin-speaking version develop" says Wells (1922, p.45). His rule was the time when State had the utmost supremacy and after his death, State power receded to the background and papacy became more important during years of Latin Christendom. It was a Latin speaking world and the States resented the enormous power wielded by the Church. By then, the Romans have become Christians and they could not abide with the papal power. Christianity started with the high principles of brotherhood and tolerance, but with the high individuality cherished by Romans, Church found it necessary to have effective control.
" Christianity did cherish the principle of toleration and abandoned it only reluctantly as the need of maintaining social, and even political cohesion among Romans made centralization and authority unavoidable," Pickman (1937, p.17).
On the other hand Byzantine Empire was the Greek speaking Roman Empire and under emperors like Constantine, it was a raw political power. Even though the emperors were totally in control, this did not rule out acute rivalry and existence of contenders to power. Rebelling against the state or defying it would have brought severe punishment. People were well protected, but had very few individual liberties. Rulers like Justinian were more focussed on empire expansion and control. Emperors did not look at the religious authority for succession, approval and guidance in ruling. No doubt the Christian power was ascending, but it did not control the political power. Byzantine rulers never accepted the superiority of the Church. The Emperor remained supreme and every other authority was defied. Byzantine were more autocratic than the States that came under Latin Christendom.
By 867 wars against Islam and Turks dominated the Byzantine rulers and also inner struggles kept them totally occupied. For a long time, the struggle continued and Byzantine could not defeat the Muslims; instead got defeated in Crete in the year 911. Byzantine Empire perhaps faced more external problems, but managed to be more progressive, while Latin Christendom remained locked in many struggles between papacy and States.
"The eastern empire and the Eastern Church performed two services to Europe: they helped civilize and teach the newly-settled barbarians in the west, and they struggled with and eventually converted the barbarians who settled in the Balkans," Deanesly (2005. p.67).
Emperors like Constantine did not even get converted into Christianity and retained enormous political clout. Constantine could encourage his people and army without calling for a Christian martyrdom in support of religion. "There has been extensive debate about the exact form of Constantine's device, but the evidence which we have reviewed so often - plus the very existence of the debate - indicate that whatever it was, it was not the simple and unmistakable cross of Christ," p.18, Key, 1982.
In Latin Christendom, those were the days when there was hardly any division between the church and state and people like Dante decried this integration and slowly emperors and intellectuals tried to separate both the functions and powers. In the beginning of 10th century, secular