Gotta be careful here.
I wrote about totalitarian regimes since and including the French Revolution, therefore my comment was not general.
Up until the end of the 19th century most civilised countries were European where Judeo-Christian morality prevailed and this morality prevailed in th colonies. This general consensus even included many non-Christian regimes. After WW1, this consensus began to fall apart.
"On the other hand, perhaps you mean that a civilisation that is built on Christianity might have difficulty surviving without Christianity. I would be inclined to agree with that." I would agree with you. The consensus even among Christians and indeed Catholics has almost disappeared in the West?
I don't know what you are fishing for when you ask, "... what kind of Christianity is needed within a "civilisation" that has been traditionally "Christian"? Is it always as it has been in the past?" Perhaps you can tell us.
V2 was concerned with being in the world but not of it.