At the end Ishgard: theocracy and history, which conclude of it? (spoil)

[MistakeNot]

I'd also like to mention, I haven't seen historians argue that monotheism was the cause of the middle (or dark) ages. The value of the Renaissance as a period, also based in monotheism, pushed people to excel.

It has been argued that Christianity was a major factor in the fall of the Roman Empire. The most famous proponent of that theory was no one less than Edward Gibbon in his "The History of the Decline and Fall of the Roman Empire". Few current historians put much weight on that theory though.

It is also a myth that the European Middle-ages was "dark". Yes, some knowledge was lost after the fall of the western part of the Roman Empire but not much, and innovation and improvments continued apace during the period.
The Renaissance was mainly a continuation of the Middle-Ages, but with some major societal changes starting to take place in no small part due to the population loss of the Black Plague.