Again, depends on what you mean by "darkness", and how close this is to the Christian descriptions of "evil".
Also, it depends on how close to what you're talking about is to conventional definitions of "illegal".
However, let me refer you to a really good book, "Diamond Age", by Neal Stephenson. It's about nanotechnology, but it also goes very deeply into ideas about where morality comes from; some of the characters strongly espouse what you may be ultimately saying: that a visceral
experience of evil is what leads someone to truly, sentiently, embrace a moral code. (In the story, there are a group of people who embrace Victorian-era mores. They did so because they came out of a post-government world collapse in which amorality reigned. They're worried about their children and children's children, who grew up in this new world with the moral code intact and who accept it by rote -- so you could say, in a sense, that they do not actually
choose it. The story is about one character's attempt to introduce
perversity* into children's education.)
*By "perversity" I do not mean sexual perversity. Rather, what Stephenson talks about is what we would call "grim" or "dark" elements -- like the (original) Grimm's Fairy Tales. By vicariously experiencing evil through the characters in the story, the hope is that children will come to embrace the culture's moral code because they see that it is a rational response to amorality. The characters seek to create children who are not afraid of contradition or paradox, and who do not automatically expect that the simplest answer is the correct one.
Religion-wise, you might be interested in my own faith,
Kemetic Orthodoxy. Part of the underpinnings of the faith is that there can be very contradictory (and even opposing) faces of God: to whit, you've got Osirus (linked to the green, growing land) and Set (linked to the red desert and to storms). Set is not
evil, in the classical Christian "SATAN!!!" sense. Set represents forces of nature that can be incredibly destructive, but just
are (and, in fact, is the only Name strong enough to face Apep, which represents
isfet, or "evil"). Evil, in the KO sense, is (sort of) Uncreation (not death, which is a part of life).
KO might twig to what you're saying; if I'm understanding you correctly, there might be some parallels.