Of our response to the sins of others, she said (ch. 76): "The soul that would preserve its peace, when another's sin is brought to mind, must fly from it as from the pains of hell, looking to God for help against it. To consider the sins of other people will produce a thick film over the eyes of our soul, and prevent us for the time being from seeing the 'fair beauty of the Lord'-- unless, that is, we look at them contrite along with the sinner, being sorry with and for him, and yearning over him for God. Without this it can only harm, disturb, and hinder the soul who considers them. I gathered all this from the revelation about compassion...This blessed friend is Jesus; it is his will and plan that we hang on to him, and hold tight always, in whatever circumstances; for whether we are filthy or clean is all the same to his love."
This reminds me of what C. S. Lewis wrote as the conclusion to his chapter on "Sexual Morality" in Mere Christianity:
If anyone thinks that Christians regard unchastity as the supreme vice, he is quite wrong. The sins ot the flesh are bad, but they are the least bad of all sins. All the worst pleasures are purely spiritual: the pleasure of putting other people in the wrong, of bossing and patronizing and spoiling sport, and back-biting, the pleasures of power and hatred. For there are two things inside me, competing with the human self which I must try to become. They are the Animal self, and the Diabolical self. The Diabolical self is the worse of the two. That is why a cold self-righteous prig who goes regularly to church may be far nearer to hell than a prostitute. But, of course, it is better to be neither.