One passage of the encyclical that really grabbed my attention was this:
"Both these things—justice and grace—must be seen in their correct inner relationship. Grace does not cancel out justice. It does not make wrong into right. It is not a sponge which wipes everything away, so that whatever someone has done on earth ends up being of equal value. Dostoevsky, for example, was right to protest against this kind of Heaven and this kind of grace in his novel The Brothers Karamazov. Evildoers, in the end, do not sit at table at the eternal banquet beside their victims without distinction, as though nothing had happened."
That's quite a powerful statement! I think it speaks to the modern tendency to somehow whitewash moral evil, as if what we do with our lives doesn't really matter in the end. But it does. What we do now will have consequences for all eternity.
That's a consoling thought for people who suffer injustices here on earth. While we rightfully act to right those wrongs, on earth, justice often is not done. When you see evil seemingly triumph, it can sorely test the faith of believers. But evil will not have the last word.