Duopolis
There has been a bespeaking rupture across the European body of peoples for five centuries now. In a rudimentary form, it can be even found a millennium and a half back, if you take the Germanic tribes’ intriguing affinity for Arianism in the 5th and 6th centuries. I’m talking about the Catholicism-Protestantism divide of course.

One aspect seems to have been usually overlooked or shoved backstage in perceiving this happening. Which is that the taciturn, less allegorically minded, more literal and down-to-earth Nordics got predominantly drawn to Protestantism, whereas lighter on those traits, more imaginative and lofty eastern, southern and southwestern Euros have mostly stuck with Rome, or with its creedal twin, Eastern Orthodoxy.
Why such a rather constant, upheld throughout millennia – if we count in the Germanics’ early crash on Arianism – divide? Was it sheer chance that in one fairly minuscule region of the continent there emerged three giants of the greatest religious dissent of post-medieval Europe: Martin Luther, John Calvin and Huldrych Zwingli? Or did population biology rooted in environmental factors have something to do with it?
True, John Calvin was a Frenchman, but first, he derived from the far-north Cambrai, and secondly, he was given a prompt boot by “the eldest daughter of the Church” after becoming a too “down-to-earth” theologian. Just as she’d clamp down on the upcoming Huguenots, forcing many to flee. And so it was in the ethnically and culturally German-dominated Switzerland (with the parts French and Italian secondary tributaries), where John Calvin found the societal soil to plant his rationally upped creed seed. Today religious Switzerland splits between Protestantism and Catholicism roughly by half, which rather upholds these musings so far.
How about Germany proper? Well, it’s another interesting one. In Germany, we see a well-established divide between the north, which turned Protestant, and the south, which remained predominantly Catholic. That creedal divide had been even more pronounced before the 19th-century industrialization, which boosted individual mobility and blurred the boundaries. Nonetheless, the contemporary map still attests to the traditional historic split – except the eastern Germany, but that may be chalked up to a prolonged Communist cap on religious attitudes, and also specific population genetics of the territories between Elba and Oder, the Slavs, etc. This last one aside, wouldn’t the fact that the majority of religious Germans in the south have stuck with Roman Catholicism (the least enthusiastic Hitler voters btw) be the result of genetic overlap with the peoples farther south? Just like the northern Italians attest to an influx of the northern populations’ genes with their legendary blue eyes, blond hair, light skin?
This last case is particularly interesting because the Lombards are said to be of Scandinavian origin, settled in the northern Italy in the 6th century. There’s a significant number of Protestants and Waldenses among them, along with the Catholics. The Waldenses in turn, of the creed nearly three centuries older than Protestantism, became fast buddies with the Protestants when that persuasion popped up in the hood. And, as mentioned, the Germanic tribes were curiously attracted to the heterodox doctrine of Arianism when they began processes of Christianization in the 5th century (the Arians, sober-headed chaps, considered the doctrine of Trinity too much of the good thing, their Jesus being “unidentical” with God the Father). Categorically condemned by Rome, Arianism loses influence on the Germanic peoples by the 6th century, and yet, ten centuries on, it has a great comeback in various forms within the newly emerged Protestantism. Telling stuff.