Based on a book about the eastern Roman empire that I read recently, early Christians certainly cared a lot about unity, particularly after Christianity became

Based on a book about the eastern Roman empire that I read recently, early Christians certainly cared a lot about unity, particularly after Christianity became the state religion of the Roman empire. But it didn't put a stop to bitter theological disputes between the bishops of different cities and instead fueled them. The religious councils were a fairly ineffectual attempt to solve them. These were disputes over power, with the bishops of Rome in particular attempting to achieve dominance over the others, even though by then, Rome was a backwater compared to Constantinople. Earlier polytheistic religions didn't pretend to be universal and therefore had more built-in tolerance, even though religious tolerance hadn't been invented yet. Rome could demand sacrifices to their gods but it was accepted that people in different cities had their own gods.