Most Christians that I know refuse to read the bible properly, then I take the bible and teach them the stuff in there, several freak out, to the point I do not do it anymore to stop freaking people out...
I am a Christian myself, and the bible asks you do not be a "stumbling block" (or something like that the english term), so I guessed that is good idea to stop freaking people out pointing those things.
Not that I won't talk about them, to those that come to me and ask I cheerfully explain everything I know about the Bible, even the taboo (for example, why the Bible regulamentates slavery)