How is sin brought into your world?

[Azaraiha]

In my world the most prominent religion teaches that two spirits, brother and sister, existed before all. the brother, also known as the "Father of Creation" decided to create the universe. Seeing the brother's creations pray and worship him, the sister got jealous and killed the Creator. Thus sin originated in heaven. What about your world?

 

[Saigonnus]

There was never a Utopia, no perfect ideal. There was light and dark. Order and disorder. Pain and Pleasure. Life and Death. Neither can exist without recognizing the need for the other. It is a fundamental principal whose power that even the earliest sentient people were away of. It was they who brought their gods into existence, their need to embrace one of these most primal forces, putting it in dominion over the others; only to have them fall and for the pendulum swing back the other way as the centuries fled. Gods have come and gone with the passage of ages, leaving only unknown ancient relics behind while other gods reign over their flocks, uncaring of the world. And there are gods yet to be born from the ashes the present pantheon will leave behind when they too pass into obscurity. Sin and righteousness have always been and will always be until the universe itself is destroyed.

 

[S J Lee]

I love the Silmarillion and all, and know the gospels and the OT fairly well... BUT wouldn't dream of copying them. Not that genesis REALLY explains where sin comes from. God merely tells Cain:
"If you do what is right, will you not be accepted? But if you do not do what is right, sin is crouching at your door; it desires to have you, but you must master it."
I see this as meaning that God isn't looking upon Cain's sacrifice with disfavour because Cain is only sacrificing plant-food; it is because there is a part of Cain that is jealous of his brother, and God sees this. It isn't clear exactly what sin IS or where it COMES from; the devil? Free will? God himself wishes it so, to make a point?
Scholars argue a LOT about "God hardened Pharaoh's heart..." in Exodus
Who Really Hardened Pharaoh's Heart? | My Jewish Learning
Towards the end of the portion, after the Egyptians suffer boils, the text says (Exodus 9:12), “And God hardened Pharaoh’s heart, and he did not hear them.” The plagues continue, but suddenly they seem much less fair.

IF the Bible / the Torah does not have a clear-cut answer to the thread Q, why do YOU need one?
The Silmarillion IMPLIES that sin comes from Melkor's desire to be a creator himself... BUT was it Illuvatar that MADE him that way? All the suffering in the world comes because Illuvatar creates Ea, Arda, the physical world, to show Melkor that "There is no music that can be played in my despite" - ie, all your evil deeds will make the story GOD wants to tell all the more poignant. That is is it. Period. Epic, but that is a lot of little people condemned to suffering just to make a point.
OR would people have been sinful anyway, even if Melkor had refused to descend into Arda? Tolkien never said yes or no.

Only create what you need to. OR, rather, only show the reader what they need to see. If you have your own philosophical reasons for why the world is the way it is, that is fine .. but 90% of your readers will get bored if you start with lengthy exposition. And the other 10 % might be conservative Christian-types, who see your book as blasphemous ....A high-stakes theology debate in front of a king wondering which religion to join might be more intersting... EG the theologians argue in front of the king, but of course it is REALLY the Writer explaining to the READER - there are many ways to make such a theme interesting. If the reader likes at last one of the priests and hates the other, even non-religious readers might find it interesting

Ideas are not enough; it is execution that matters....

 

[Insolent Lad]

Sin/Evil vs Good is seen as an 'artifact' of the interaction of Being/Existence and Nothingness/the Void, rather than a thing in of itself. As is the struggle of chaos and order, or any other duality—they all reflect that fundamental dualism.

 

[S J Lee]

So, as for myself, I have people with VERY strong opinions of right and wrong, and heroes VERY willing to kill people for evil deeds.... but they think in terms of "evil", not "sin"... no real "gods", and what "gods" there are don't always have much to do with "real morality"

EG, ask a scientist why fire or rust or slow-growing crystals are NOT alive.... and you may find that is is harder to define "alive" than you think! As Lucifer said in the Lucifer comic strip, when angels / demons / gods duel in Effrul, the fight continues until somone gets their heart cut out (they must have a heart, and it must be present in the duelling arena)
"Why not just fight to the death?"
"Death for gods is sometimes difficult to define"

"Sin" may just be a name humans give to an abstract situation... like beauty/ugliness ... justice / injustice ... life / death ... war / peace

When does a peace-keeping action become a "war"? When does a riot become a revolution? When politicians say so? It's just a name given to a pattern, a situation that humans think is relevant, something they feel the need to describe. There is no need for it to be objectively real... ie, sin does not enter the world like some comet entering the solar system. Someone is the FIRST to sin, but so what? It would have happened anyway....

 

[S J Lee]

In other words, don't have "a complicated origin of sin" that means nothing to you personally. If you have "religion and theology" in your world "because a creative writing teacher told me that in Ye Olde Medieval Europe settings, you MUST have them"... but they mean nothing to you personally... you yourself care nothing about it one way or the other.... it will be fake. Hollow. Readers will see it and turn off.
BUT if you are "overly preachy" to people who only want "harmless entertainment" ... they will switch off too. Lots of people don't like Christian apologetics.
Just give them entertainment. Hook them with thrilling characters in a thrilling story. And THEN hit them with ideas really worth thinking about IF you have any...later on in the story. Once they are already committed because the story is good / thrilling....

In other words, is this just a detail of the setting, as unimportant as whether they use spoons and forks, or sporks? IF so, is it really worthy of ink on the page? OR do you actually have something to SAY on the topic? Eg, the Chinese scholars etc debating "Thou mayest" in Steinbeck's East of Eden....
GRRM has a bit about the worship of the Seven, but doesn't go near anything as profound as "Sin", nor its origin. He isn't the kind of writer to have profound or original thoughts on such matters... or he hides them because he assumes all that readers want is to see Jaime f--- his sister. He doesn't bother putting in profound origins of sin etc, it is not his selling point. All the better for it.

of course, this is just one person's opinion...