Well... For people like me, suffering is a test of faith, and strength. If you can go through the trials life makes you face and still be kind, still believe, then that means you are truly loyal to God. [To put it incredibly simply. Imagine turning to God in one's absolute worst moment, for instance 8D/ Rather than cursing Him instead.]
It doesn't have to involve faith, too. There are plenty of people who have suffered some of the worse evils in the world, and still remain kind and decent. It only goes to show what truly remarkable people they are, to not turn bitter or hateful over it. [He's 100% thinking of Porthos there, although it technically applies to him too, and obviously to Korra herself.]