Sunni and Shiite are older and more confusing than Guelph and Ghibelline and far more important. Thus, if you’ve been reading Dante since 1963, Guelph and
Ghibelline are mere good clean mental fun. Serious European religious wars began with the Reformation and ended, more or less, with the Enlightenment. The Reformation had been a war between Protestant and Catholic. Islam and Christianity had already warred for 800 years. The Turks conquered Constantinople and reached the gates of Vienna. Earlier Islamic armies conquered Spain and Portugal; was Roncevaux in France the high point for the Saracens? How enlightened, then, was colonialism? It was an unrelenting world-wide cultural and religious Crusade which burnt out with two World Wars and finally a long Cold War. Here we are. I preferred the Ghibellines myself.