I think the song's about feeling like you're worthless and being considered a "pig" and a "filthy swine" by others around you, and having rumors being told about you (murderer, terror, killer), but at the same time you feel "set free" because you're your own person and telling the people to "[not] read the writing" to judge you on your own character instead of rumors.
But that's just my opinion, from my own experiences.
I think the song's about feeling like you're worthless and being considered a "pig" and a "filthy swine" by others around you, and having rumors being told about you (murderer, terror, killer), but at the same time you feel "set free" because you're your own person and telling the people to "[not] read the writing" to judge you on your own character instead of rumors.
But that's just my opinion, from my own experiences.