basically unconditional diagnostic like "you are idiot" may be considered as insult by most people.
If they are argumented, those diagnostics may be factual, or at least subject of a debate.
Anyway best is to avoid unconditional statements on people, even on class of people (not easy).
On the opposite conditional statement like "your position is irrational", is better fitting a debate.
It is best to do. I'm sure THH who showed a wide capacity to argument while staying correct, will have this capacity.
Another point, don't think you can convince others. Many positions are based on ignoring some points, or interpreting them differently because of unproven/unshared hypothesis or heuristics. Finally many beliefs are tightened to inner values (sometime through former commitments, stakes), and changing a beliefs requires much more energy than breaking the coulomb barrier or bankrupting Lehman Brothers.
Stay polite, state conditional judgement on others "your position on AAA is XXX according to me", propose evidences, and interpretations, answer to interpretations, and don't wait for your position to be shared.
You cannot save everybody, but you can save yourself.