Turns out that Jonah's decision to initially avoid going to Nineveh had little to do with being scared of teaching the people there, but instead, "it seems to have been resentment against the Lord for giving the hated enemy a chance to repent." (Old Testament Institute Manual). Wow! This was a new principle in the book of Jonah that I had never thought about: Are we okay with God extending mercy towards our enemies? Elder Holland gave a masterful talk on this principle entitled The Laborers in the Vineyard. He said "Brothers and sisters, there are going to be times in our lives when someone else gets an unexpected blessing or receives some special recognition. May I plead with us not to be hurt—and certainly not to feel envious—when good fortune comes to another person? We are not diminished when someone else is added upon...God really is both just and merciful, giving to all who stand with Him “all that he hath,”2 as the scripture says.”
The perfect balance that God strikes between justice and mercy is something that I'm still trying to more fully understand and better implement as part of my personal character. It is hard. I can relate to Jonah in this story as my personality tends to lean towards applying the principle of justice in most situations. For example, when I've told my children over and over not to... (i.e. climb on back of the couch) because they are going to fall and get hurt and they ignore my warnings and proceed to fall and get hurt, this "justice-leaning-mother" shows little mercy and and says "I told you that was going to happen." (Fortunately I'm married to a merciful husband who comforts said child in their distress). But God's reaction to Jonah's attitude toward the repentant Ninevites is obviously disappointment (Jonah 4:10-11). And I think He feels the same about us when we refuse to extend mercy and compassion to those who are repentant and willing to change, whether or not we think they deserve His mercy. The Lord will forgive whom ever He wants to forgive, but He requires us to forgive all men (D&C 64:10).