a book i recently obsessed over, the private memoirs and confessions of a justified sinner, more or less revolves around this error, summed up in the authorial voice by the parable of the pharisee and the publican, luke 18:9-14, or in hogg's phrasing 'the just pharisee.'
vindictiveness or self-righteousness is itself sinful, it is the essence of pride, though it's true that to wag a finger is to make the same mistake gregory did, to tart yourself up in others' failings.