Frank Schnittger:

I'm not arguing that national boundaries are not a factor, merely that you cannot presume, a priori, that they are a given, or the most important factor.

...

The more interesting/explanatory analysis may be by religious/non-religious background, age group, rural/urban, class, occupation, education level, linguistic abilities etc.

The question of explanatory power is presumably an empirical question, unlike the question of what is "more interesting".

Most economists teach a theoretical framework that has been shown to be fundamentally useless. -- James K. Galbraith