> For example, when someone calls a statement "x-ist," they're also implicitly saying that this is the end of the discussion.
I tried to recall the few times I called someone out on being sexist, racist or whatever, and it was never a discourse or a discussion: the majority were tasteless jokes in the presence of someone would have been affected (e.g. tasteless joke about how all women are $X in the presence of a women which very clearly was the polar opposite, or how all people with a certain enthnicity have a certain negative trait etc.
These people were not guilty of heresy they were insensitive assholes (when done on purpose) or at least ignorant.
In an honest discussion with someone about e.g. the differences between men and women, I never called someone a sexist, just because their ideas were outdated and flawed as long as it actually was an discussion. The thing is, that more often than not the goal of people spouting such things is not getting to the bottom of things, but validating their own opinion. This is of course out of insecurity, which is why calling someone sexist is not a good way to respond in such an situation. Better is to ask them what they mean and have them explain it to you. And if they realize themselves they are sounding a bit odd, you can just tell them this is not your experience.