I agree with gore, sexual scene and mature content, but I wouldn't put nudity, unless it's erotic nudity (which would be like a soft sexual theme warning). I think that non-sexual nudity shouldn't be viewed as something NSFW because it contributes to the sexualization of body, and to comfort the position of rapists who abuse persons under the pretext that they were too lightly dressed. It doesn't matter if someone is naked and hot, that doesn't grant anyone the right to rape them. And characters in comics are characters, not real people, so one should be able to look at their nakedness without being all "ew, that's obscene".
As for Ideologically-sensitive topics, it requires in the first place that the creator be aware that what they put up is sensitive, which isn't always the case... what is offensive to one isn't to the other. Like, if you take a story with religious characters, if they are being very puritan and with a position in which they consider gays to be disorderly persons who'll burn in hell for eternity, you are likely to offend LGBT persons, while if the same story is sided with gays criticizing religious persons as a whole, you are likely to offend religious persons.
It's also why I think creators should thoroughly research such polemical topics and understand both sides before even trying to put up this sort of plot (especially if it's to express a manichean vision), but what I meant here, is that as soon as we take a side, not matter which, we're likely to offend someone else's ideology. So such a warning tag should come with a definition to sort out what is really likely to be offensive or not.
To me it's ok to (wisely, please) bash, say, religion when it leads to narrow-mindedness instead of spirituality, and enforces that it's ok to bash certain people for their race, gender identity, sexuality, etc, thus endangering their basic human rights. But it's not ok to bash religion as a bundle of symbolical beliefs in which one seeks spiritual elevation and peace, just because the creator (like most religious persons actually) doesn't understand what God is/means.
In that regard, I think it would be nice to have the possibility to pull up a text description for those who don't want to click but want to keep reading the story. Ie: "In this scene the car crashes and the kid sees both his parents dead and covered in blood, remaining with them for hours until a stranger comes to the rescue and takes him out of the wrecked vehicle."