It depends on how "real" you wish to attribute the non-human entities and spirit(s) said belief systems revolve around. As I would guess you are doing now, you can easily have a philosophical discussion while dismissing them as more "ideas", constructs, or placeholders for ideas we create as opposed to a what many believe, true actual beings that may or may not influence the world we live in. That changes things quite a bit.
For example, you could say a "god" or "spirit" is more of a zeitgeist of human society, a man-made construct divine in the sense that indeed it has power over any one of us. If one group or town challenges another to battle, they are invoking this "god of war" but if they instead pray for peace they are appeasing and placating this god (or perhaps invoking an opposing god, say "god of peace") and "they" battle per se. It's a stretch but metaphors are allowed and such are still considered non-theist philosophy. Your civilization can appease or act on the instructions of a "god of wealth", which assuredly involves being prosperous, but perhaps being too prosperous would anger this god, invoking wrath. Ie. your people become too rich and everyone just starts getting lazy and before you know it doesn't know how to do anything anymore and falls like a tree to a group you outnumber 10 to 1.
On to more traditional theist beliefs, yeah. They're as real as the screen you're reading these words from. Some are good, some are tricksters, some people believe there is only one creator, others believe this not to be the case. God(s), false gods, spirits, good, bad and all things in between. Depending on who you ask of course. So as a theist, how does one know what to believe? The consensus between major religions would be prayer and humility. How can you learn if you don't listen? Why would you be helped if you don't deserve it? But again, it depends who you ask.
We are exploring what that has to do with liberty and being free souls versus being institutionalized. A spiritual notion is we are free spirits having a human experience. This spirit is connected with the force of life, our planet, and all life on it, rather than the external Father, Son, and Holy Ghost of Christianity and the Roman Empire. — Athena
Free soul or not, you reside in a very physical body, burdened by physical needs that must be met and influenced, if not controlled completely by primal instinct that only becomes more insatiable and savage when said needs are unmet. Due to this, I'd kindly suggest that perhaps your argument of "either or" is somewhat of a false dichotomy. Just a smidgen.
If everyone is running around, being free, meeting their physical needs along with various, often unreasonable and decadent wants, somewhere down the line someone's liberty is going to be restricted. That
is the definition of being institutionalized. Being in a confined system (life) being told what to do (instinct) with no say over the external or "overarching, unchanging, otherwise unreachable" authority that makes the rules (biology).
So, one could suggest the divine rule over all mankind (free spirits while we're in our physical bodies here) thus ensuring true liberty for all from an omniscient being is not only highly preferable than otherwise but is truly the only escape
from institutionalization of not just not the body but most of all the mind. Sure if you're lucky and never have a problem in this life perhaps you won't ever realize its importance, but if that ever happens to not be the case, one would begin to appreciate the notion- and rather quickly, I presume.
In conclusion, who freakin' knows. I just do my best to try and not be a douche and hope for the best. If I'm not mistaken that's pretty much the summary of 95% of all religion anyhow.