dragodon64
Noble
Nationalism as a concept wasn't around for many hundreds of years after the split of the Frankish empire.
I disagree with your view that "culture and language did not diverge in that area because of a schism".
My view isn't that there is only one reason for the differences today between France and Germany, but that a significant reason for the differences between France and Germany can be attributed to the splitting of Charlemagne's empire amongst his sons at the time of his death. And I don't think that this is an "absurd" concept either.
In review, I felt that I was too harsh. Sorry for taking your statement the wrong way. I completely agree that the political division was a factor, though I don't believe it was as much of a factor as you do.
Also, the borders of the Roman empire were quite moot by the time Charlemagne came about, as Gaul had been thoroughly penetrated by various Germanic groups, the most important of whom were the Franks.