I have an untested theory that the thing to do with individuals deeply into some ideology/conspiracy theory is to first agree (and get it across emotionally) that if things really are like they say and *spins wheel* the knights templar really are out to *spins wheel* cannibalize babies via *spins wheel* installing 5G hotspots, then yes, that would be bad, their reaction would be appropriate, and we would have to do something about that.
It's counterproductive go facts-first with people who feel attacked further by anything but that one thing they want to hear - which is that you don't agree with it, also want them to die or whatever, or don't care. After establishing you are on their side in terms of values and goals, it might turn into establishing what exactly the facts of the current situation are.