Christians, know your lineage

[coffeeveritas]

These two were actually one church until the 11th century

Are you sure?

Isn't the Greek Orthodox Church part of/ an offshoot from the Byzantine church in Constantinople?

I was under the impression the schism goes back to the First Council Of Nicea, (325 ce)when the Canon was set and Rome (and the Pope of Rome) was declared the head of Christianity. The Christians of Constantinople did not (and do not) use exactly the same canon and did not (and do not) recognise the Pope as head of the Church. (??)

Or have I gone and gotten all confused again?

Well, there really wasn't a Pope in the sense we think of it until around the time of Pope Gregory I (590 AD), even then the eastern part of the church was never big on the whole "pope" thing. Before that the pope was just the bishop of Rome.

There wasn't a schism at Nicea, although there were certainly disagreements. The eastern church actually agreed with the council, but trouble started brewing throughout later councils. There actually was a kind of schism between the eastern and western churches as early as the mid fifth century due to the fact that the two sides of the church were largely isolated from one another due to conflict in the Italian peninsula. This was more geographic than anything, and the church still considered itself one unit. The official split wasn't until the 11th century though, as noted.