In the history of ideas do you think that the concept of denomination existed in the fourth century AD?
It seems unlikely that any denomination existed before the early 4th Century, when the Roman Empire created one (in its own image) for its own self (it never existed outside the Empire), as a geopolitical/economic/legal entity linking together the thousands of parishes now suddenly legal in the Empire (they thus become owned and operated by the newly formed Roman Church).
Prior to that, Christianity was primary an ILLEGAL and largely underground movement... very, very loosely connected and with no organization (much less denomination!) owning and operating parishes. Customs, languages, even doctrines seem to have varied... things were pretty "loosy goosy". As we would expect in an underground, illegal movement. The Roman Empire changed all that - by first making it legal and then almost immediately making it The Empire Religion and Organization - the State Church. Rome loved (well, Rome was OBSESSED) with POWER, CONTROL, AUTHORITY, CENTRALITY.... "loosey goosey" was the antithesis of anything Roman. Rome wanted as much conformity of teaching and practice as possible - and so the EMPIRE called councils and demanded decisions. The Empire set up it's religion as a mirror image of itself - top down, all about power-control-submission, "lording it over others as the Romans do" as Jesus summerized it. The first denomination was born.
Now.... it is true.... before this, there was a very, very, very informal, unstructed, and rare collaboration. The Jerusalem Council in Acts 15 is an example of Christians at least in some way connecting beyond the congregational level. Paul's collection for the relief of the saints in Jerusalem is another. There were rare, limited, informal areas of connection and cooperation before Rome created the Roman Church for itself, but there's nothing there like a denomination.
Now, More Coffee has claimed that no denomination existed before the year 1200 AD (which of course means the RC one didn't) but I don't agree. A case can be made for none before the early 4th Century but I think there clearly is at least one denomination created then. It was just for the Empire and so not "catholic" in any sense, but I think a case can be made that there was just one Roman one for the Roman Empire created by the Roman Empire for itself. But it split in 451 (actually fragmented).... and again in 1054 (the largest split in all of Christian history).... so there were several denominations before the Reformation came around. And then there were all those churches (in early Ireland for example, in India also) that were not in ANY denomination for centuries.
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