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The world of Spiritias had gone through many religions as far as I know, and there might have been even more in prehistory, back when the Living Gods such as the Divine Dragons, Titans, and the Elemental Spirit Races lived around the entire planet before the war that killed most of them and left the mortals to inherit the world.
In these ancient times not only did they create the power of Talents, Levels, and Skills themselves, somehow finding the ability to use specific giant devices to imbue a soul with these powers, which I would simply call "Soul Book" that allows every person in the world to be able to Level Up, learn Skills, and such.
It has been mostly a "hidden power" where people could only estimate what they had and how it worked approximately, without many ways of being able to see it as clearly as my Grimoire…