Our reasoning back when we did the Charlemagne expansion was precisely that the actual differences were relatively small and that there were no official instruments of doctrine to divide the faith politically. So we decided that the situation didn't warrant adding a separate religion for the realm of Saxony.
Also, CK2 veterans will remember that the religion used to be called Norse in the game, but with the Charlemagne expansion (and the free update) we decided to change the in-game name for it, both to reflect its wider scope going beyond just Scandinavia and also to avoid players confusing it with Norse culture.
Also, CK2 veterans will remember that the religion used to be called Norse in the game, but with the Charlemagne expansion (and the free update) we decided to change the in-game name for it, both to reflect its wider scope going beyond just Scandinavia and also to avoid players confusing it with Norse culture.