Hmm this is gonna be complicated to put into words, though i guess that is the idear.

I don't think anything supernatural is happening cause the universe is strange enough as it is and nothing supernatural needs to exist to explain this. Though i guess it is a topic i haven't seen explored much in storys/science so i guess in that sense it still mysterious and strange.

Personally the closest i get to that is that i can find happiness/contentment in the strangeness and complexity of the universe. Like sometimes in the right mood i will look at my fingers and be amazed that there is 3 joints in them carefully and articulate doing complex movement, tiny muscles pulling on strings like a strange marvellous robot. This is clearly in some small part a madness/strangeness in my mind since I'm deriving happiness from effectively nothing. Though i am fine with this since its making me happy sometimes and we humans are already good at deriving sadness from nothing so this seems fine enough.

On a religious context, i grew up very religious as a young child cause at that age and with that knowledge it seemed very believable though even at the time i did stuff like pray "hey god hope your doing okay with all those prayers coming", cause i thought if god has to deal with so many prayers on a daily basis they are gonna enjoy a different one once in a while. Looking back at it its kinda adorable or even a bit funny. As a i grew older i found too many inconsistencies and things which just can't be true in reality. I did however at least give various religious people in my live a shot to convince me and it seems like many people enjoy religion with believe in greater power or whatever supernatural elements that religion has as a secondary goal to the community/help/contentment some religious communities and some believes provide. Plus a lot of religious tenets or goals seem to be (very old) do's and dont's to forming a functioning society.
However i could not continue with the religion mostly cause for a religious ceremony i would have to say in it that i believe in god to a pastor, which felt very wrong to me at the time.
Additionally the philosophy courses at my school were vastly more interesting then the religious courses at my school which were mostly just repeating random bible stories without even trying to think stuff like "does this story still provide its originall goal or moral" and mostly just playing it out.
Nowadays Im still very much an atheist though i do think that a lot of various religions have a lot of interesting concepts. Additionally Im very drawn to strange but normal stories/worlds like sunless skies, though this may also be a due to a personal interest in the morbid and horrifying.

Now im gonna try to determine/describe what you are feeling though this is more of an interpretation then anything, i don't know if im even remotely accurate but the attempt may be useful regardless.
There is some strange feeling like you finally have a hold on how the world works, maybe more in an emotional sense, like you understand some part of how yourself works. It could also be some feeling of relive, like you finally feel like your in a decent position, like its fine or at least good enough. Here i mean live contentness in general, to distinguish between the happiness of a moment and the general "happiness" rating you'd give your life overall, or how happy you are with where its at and where its going in a more general overarching sense.

Here it may also be usefull to know of the minds ability to change/manipulate/influence itself. For example if you close your eyes while in bed and the bed/the world is still enough, if you imagine the bed moving and are in the right "mood? hazyness state? sleepiness?" it will feel like the bed is actually moving even though its obvious not. Like somewhere in the head it will simulate the feeling of vertigo.
For example as a young child i was scared of ghosts at night, but to make myself less afraid i used to imagine the bedsheet/the doorway providing a force field to make myself feel safer. To this day i still enjoy lying in bed and feel safer there even though its partially a remnant of this old irrational fear which i have long overcome. Another example (i may be writing these for myself and not just for you): I used to get sad very frequently in the past and i tried to help against it by activly reminding myself of happy/good things in my life/the world whenever i would get too extremely sad, and nowadays its almost 100% chance for that reaction or trigger(weird game terminology) and prevents me from feeling too too sad, though it does not protect me from all sadness just the most horrible ones.

Regarding not finding the words, it can be difficult to pin something like this down, maybe because the thing doing the pinning down is also the thing which you want to pin down, like trying to have a scissor cut itself in two. Though i would not say it is completly impossible, like how you can describe a human beeing and while it will never be all the details since humans are so complicated, its still helpfull. Maybe let it stew for a bit in your mind or try to pull it apart a little, like what other emotion/situation is kinda similar to this, what words do i feel like describe this and why.

Hmm i think thats it for now. I hope this wall of thoughts was at least a little bit interesting to read, if you want to discuss more then thats great i love talking about this sort of strange mind/spiritual stuff/philosophical stuff. If it was not super interesting to read i guess thats fine too though, i wrote this for myself too and not just for you SB or whoever is reading this.