State and Church
For someone not experienced in religious affairs, more so for an atheist, it is very difficult to understand the differences between the Orthodox and the Roman church, the antagonism and even at times bitter infighting between them. It is evident that mostly it has been a struggle for power and influence, trying to gain territory that belonged to the adversary.
As to the differences of liturgy and dogma, the unified churches of Eastern Europe are closer to many orthodox churches, than to most catholic ones. Also among the Catholics there are wider gaps and animosities between Latin American branches and Rome, than between for example Serb and Russian orthodox churches.
I believe the main difference between Roman and Eastern church is in the relation between ecclesiastical and worldly power. The orthodox churches are national churches, the priests and patriarchs always considered themselves the first patriots of the country and their most important aim was to serve their nation. The rulers of the countries of orthodox faith knew they could count on their clergy in their nation-building. And Constantinople always consented to the idea of national churches, as a means of still maintaining themselves as the main ally of those new entities, states or dioceses. So Simeon founded a Bulgarian Patriarchate in 917, and Stefan Dušan founded a Serb Patriarchate in 1346. Orthodoxy has played a decisive role in the Balkans: it was the Serb resistance, backed by their church, that finally drew out the foreign rulers out of the Balkans.
A different relationship than with the Balkan’s rulers developed between Constantinople and Russia.