I've been reading A Short History of Byzantium by John Julius Norwich. I haven't finished it yet, so this isn't a review, just some first impressions. I didn't know much about the Byzantines before I started this book and all I can say at this point is that they were seriously deranged. The spread of Christianity through the pagan world seems to have produced a wave of psychosis in the eastern half of the former Roman empire.
The Byzantine rulers were insane. Constantinople was always more Greek/Asiatic than Roman and the Byzantine emperors were heavily influenced by Muslim and Oriental customs in general. They were sadistically cruel, for one thing. They would blind their political enemies, cut off their tongues and noses, castrate them, burn them at the stake. Castration was used--sometimes on their own children or the sons of their rivals--to prevent them from taking power in the future (emperors had to be able to produce children). These weren't isolated events, either. This kind of thing happened all the time. The book's an endless litany of horrendous executions and maimings committed as a matter of routine by pious Christians.
The new religion didn't moderate their behavior at all; in fact, it just gave them more reasons to commit murder and mayhem. When they weren't torturing children or losing wars they might have won if they hadn't executed or exiled their best generals, the Byzantines would fight with each other and the pope in Rome about the true nature of Christ and other burning issues in Christian theology. Was Jesus more spirit than man? Were icons a form of idolatry? Idiotic doctrinal disputes like these divided and weakened East and West, still nominally parts of the same empire, and both sides would stage rigged conferences to try to resolve them in their own favor.
A common belief about Christianity is that it tempered the violent spirit of the pagans and was a force for peace, mercy, justice and moderation in the classical world. Nothing could be further from the truth. I can't decide if Christianity drove the Byzantines insane or if it simply had no effect on their already despotic behavior, but I suspect that there was something particularly toxic about the combination of Christianity, Oriental culture and dynastic politics.
Some of the Byzantine emperors were more effective than others, but for the most part they were unfit to rule and some of them were literally crazy, little more than brutal, dimwitted psychopaths with crosses hanging around their necks. In many cases, they were so hated and oppressive that they made the Muslims look tolerant and enlightened, and a lot of their subjects must have secretly wished they were still living under the old Roman emperors. Pagan Rome had plenty of political and social violence, not to mention its civil wars and dynastic conspiracies and murders, but the old Romans never came close to the level of sadistic violence routinely practiced in Christian Byzantium.
According to most histories of the fall of Rome, the empire continued for another thousand years in the east after the fall of the western half of the empire, but there was nothing particularly Roman about the Byzantines. They kept the forms and institutions of the Romans, but their empire was fundamentally Greek and Oriental, a good example of what Spengler called the Magian Culture (1) that grew up in the shadow of the classical world. For all practical purposes, Rome died as a culture with the barbarian invasions and the rise of Christianity. Byzantium was Rome's crazy mutant offspring.
A Short History of Byzantium is a fantastic book, full of sex, murder, war, betrayal and intrigue set against a background of foreign invasions, plagues, mass slaughter, religious riots and general chaos. Highly recommended.
(1) The Magian Culture included "Muslims, Jews and [early] Christians, as well as their Persian and Semitic forebears," according to Wikipedia. Spengler believed that the Magian Culture was completely separate and distinct from the classical cultures of ancient Greece and Rome, but that it had never been able to develop naturally, being forced to take on the outward forms of the dominant classical civilizations of the time, a process Spengler called pseudomorphosis.