@Big Ed MagussonMost readers have read enough to grasp the basic concepts of fiction. Not everyone though, as there are many who think that ALL fiction is autobiographical, but imbeciles are all a part of the game, someone always has to stir the pot.
As far as 'unmentionables', one way to avoid those are to have another character relate it, as that way, the character who was involve edits their language. However, that only covers a few select, third-party cases (i.e. the primary characters weren't involved.
That said, if it does bother you, try a simple substitution. When discussing religious issues, rather than referring to God the almighty, I instead use a modification of the older Hebrew spelling, g*d, with a lowercase "g" since he's not my god.
So using a similar situation, you could use "You bloody k*ke!" As again, the word is plain, though by disguising, you take the edge off of it, indicating you, the author, are distancing yourself from the term.
That said, cursing is a normal part of fiction, so it makes no sense disguising exited utterances, as "FUCK!" is much more visceral than "Gosh dern it all!" from 50's television frequently usage.
And again, since certain terms are restricted (i.e. censored) when I want to refer to someone specifically, I'll again spell it "N*zi". There is no disguising that, though it denotes that you're not an active supporter.
As they say, sometimes you have to call a Nazi a Nazi when you're not one yourself.