First, I recognize that this question presupposes some massive generalizations and I apologize for that. I am looking sort of for general answers, but specific ones work too.
This question occurred to me as I was reading the Wikipedia article on the Walk to Canossa. The article says that "[f]earing further rebellion among the German aristocracy, Henry felt he had to have his excommunication lifted." I was surprised -- I would have thought a truly pious person would be more motivated by the thought of having their eternal soul damned to hell (you'll have to forgive my unnuanced views of contemporary theology) than the potential for a temporal power struggle.
Now, this particular example could be a result of a misleading Wikipedia article but it got me thinking and I'm interested -- I'd never thought too deeply about it, but I'd always kind of imagined pre-Enlightenment Europe being almost unshakably devout (which in retrospect just seems silly). The next example that came to mind was Henry VIII, who took a pretty big risk from a theological perspective for temporal reasons.
So was I wrong? Were there atheist/agnostic/indifferent monarchs in those days? Or were most of them indeed devout Christians?
Annales historian Lucien Febvre showed in his work The Problem of Unbelief in the Sixteenth Century: The Religion of Rabelais that atheïsm was basically unthinkable before the enlightenment. This meant that even for critical thinkers like Rabelais is wasn't possible to be an atheïst, the notion simply didn't exist in the mental vocabulary.
One could be critical about religious practices and beliefs, ofcourse, but not about the existence of god.
I can't really answer for the way particular monarchs thought about the role of religion in controlling the populace, maybe you'll get another historian to answer that for you.
Hi there, this is not to discourage further answers, but a very similar question was asked here about two weeks ago. This answer might be of interest to you:
Many were both legitmately pious and able to use religion for political ends. The two were seen to be one and the same thing.
Alfred the Great personally participated in the translation of many religious works. His own writings indicate that he personally believed that he was responsible for the spiritual well-being of his subjects.
This happened as he was trying to unite the English-speaking people against the threat of pagan Viking invaders, as well as improve the education of the clergy to better serve as local administrators.
So one could argue that spiritual and political ends were seen as one and the same thing by Alfred.
I can provide some thoughts on this from the POV of Tudor England.
I think one of the most common modern misunderstandings of how religion was seen in historical times is that we underestimate how closely religious faith was tied into the rules, bonds, and power structures of society. Today those ideas are quite separate - but in Tudor times, for example, questioning religion would be equivalent to undermining the government.
English monarchy derived its power entirely from the idea that royals where hand-picked by God to rule. Essentially, it was in the best interest of the Royals to reinforce religion among their subjects as a mechanism for maintaining their rule. This means that any discussions of religion were closely linked with the balance of power with in the kingdom.
This is not to say that royals were nonbelievers using the power of religion only cynically - on the contrary, a royal raised from birth with the idea that he or she was anointed by God was even MORE likely to believe strongly in religious doctrine.
However we do see cases where the reading of religious doctrine varies according to personal interest. Henry VIII's break from the church in order to marry Anne Boleyn and establish himself as the supreme ruler of the church of England is a great example of the mixture of the personal and the political determining the direction of religious belief. That particular decision - one that had huge consequences for the country of England as well as its the rest of Europe - resulted from at least the following factors:
Essentially because the belief in God was so closely tied into power structures and government of this time, it becomes hard at times to differentiate between what various rulers did for political and personal reasons versus what they did sincerely for religious faith.
Religion was great when science wasn't able to explain basic things like what's that yellow disk in the sky? To this day, the majority of people don't want to come up with their own opinion of death and the afterlife, so religion gives them something to believe in. As for organized religions though, with all of the strict rules and harsh punushments, it's definitely used to have power and has been since the beginning. Easiest way to control people is explain what they can't, create rules and punishments to tell us right from wrong, and judge all nonbelievers.