This is one I have trouble with.

If the other side (not to say enemy) engages in uncivil non-discourse, there's no basis for respectful discourse. Indeed, there's no basis for either discourse (they're not listening) or for respect of the other side (their behavior in this hypothetical example is shameful, not respectable).

However, I'd avoid name-calling and insults, even if the other side fails to live up to this minimal standard of being an honorable human being. Not because they deserve it (they don't), but because I want to stay true to who I want to be.