If one believes the truth, one is entitled to confidence in one's beliefs.
Progressives have little confidence precisely because they are aware the beliefs they are supposed to hold are lies. The shrill hysteria they emit is a reaction to these doubts. They are terrified of anyone noticing their doubts - or rather, the certainty they hold in the falsehood of the creed. They wish to browbeat you into believing, and likewise they wish to browbeat themselves into believing.
Christians have many crises of faith for the same reason.