It's less of an ideology from games and lore and rather philosophy. It has long existed, and may have found ways to mold it or interpret it. In TES, the concept is that we are but apart of the dreams of dead gods, and realizing that alone grants us power over the perceived reality.
Mildly similar to solipsism, where only two things exist, your own mind and your thoughts, and so is a belief that nothing can be known to exist, and no one else can say otherwise, for it relies on the individual. To a greater extent, this can bring to question, are we the the mind or the thoughts? Thus, are we the product of a greater force and for what we perceived is does not really exist, thus a lack of self individualization. As with CHIM, realizing you yourself are the product, not the master, grants you untold knowledge and the one thing thoughts are void of, self identity. It's a powerful thing, on that may as well be beyond the mind itself, for even it is subject to a percieved reality
As with the Creed, it follows more of the tradition "testing grounds" set out by said creator. To know that you are put a pawn in a game reflects to my earlier reference. To know reality is but a fake, then why to should it's rules? Much of the game drew inspiration from a novel called Alamut, and held many Islamic values of belief. This falls into the "testing ground" thing from earlier. However, even if you can master yourself, the philosophy is aimed more for justice than cruelty. To live forth to peace, and undo the sins of man by removing those of terror. This is why they avoid killing of innocent, betrayal of brothers, and unity with society. As with the trends of belief and ideas, they cannot be truly killed, for they can arise anew
I hope this may of helped
