For behind the unwillingness to judge lurks the suspicion that no one is a free agent, and hence the doubt that anyone is responsible or could be expected to answer for what he has done. The moment moral issues are raised, even in passing, he who raises them will be confronted with this frightful lack of self-confidence and hence of pride, and also with a kind of mock-modesty that in saying, Who am I to judge? actually means We’re all alike, equally bad, and those who try, or pretend that they try, to remain halfway decent are either saints or hypocrites, and in either case should leave us alone.

Hannah Arendt (1906-1975) German-American philosopher, political theorist
“Personal Responsibility Under Dictatorship” (1964)
    (Source)