I'm currently reading a brilliant novel by Cristopher Moore entitled (those of you that know the book should prepare your squee-bladders) "Lamb". Without giving a bunch away, "Lamb" is the story of Levi who is Biff, a man brought back from the dead to write a new gospel for the Bible. Why? He was Jesus' childhood pal, that's why.
This got me thinking about lines. Writing, as with any art form, is about a lot of things, not all of which I care to discuss. It is, however, about pushing boundaries. The problem I see a lot is when people don't understand the difference between pushing a boundary and crossing a line.
If fiction pushes a boundary, it also pushes the reader to think about something in a new way, or more than they did before.
If fiction crosses a line, people will stop reading your book--and they won't think.
I know, I know, we're supposed to enrage our readers. But we're not supposed to enrage them through the very nature of our work. We should enrage them by killing the fairy they've developed a two book relationship with, or having our heroine go on a date with a flmaing asshole--something in the story that works. When you cross a line, everyone can tell.
Imagine if you were sitting down to read, say, Fahrenheit 451, a great book. You get, say, a third of the way into it and, for whatever reason, find a three page long dissertation from a loosely disguised author-insert character about how the Jews should ahve burned.
You crossed a God damn line there--I know because it gave me palpitations just to type it. I want to say it now--I do not agree with what Hitler or the Nazi regime did, nor will I ever. I think it's sick and vile and, if there is a place of eternal torture for wicked souls, may they all be trapped down there. I used it because it's a clear crossing of a line--but some people think it's all right for the art.
It could be, if there was a reason for it. You really are free to write what you like, but I suggest you have a reason for every damn word you use. If you use said evil, vile, nasty rant as foreshadowing, or to show something about your society, it can actually work--but just having it sit there, unadorned and not part of the greater feel of the work, is when you start to cross a line.
In general, jsut please be careful about how far you go. At some point, you'll stumble pushing that boundary and, whether purposeful or not, you'll cross that line--know enough to fix it.
Once more, I would like to make it blatantly clear that I am not anti-semitic, or pro-death for that matter. It was an example meant to instruct. If you want to throw flack at me for it, I will ignore you.