Some say that God is not responsible for the sufferings that occur in the world. The principle of causality explains why we suffer or have joy. God has created a world where causality appears to reward good thoughts and behavior, and penalize evil thoughts and behavior. The following is a quote from the Osashizu:
If I say “causality,” you probably do not understand it. The entire world is a mirror. Although all human beings go through births and rebirths, each way you have used your mind is accurately reflected on your body. Understand this well. February 15, 1888
Sometimes we think that we must punish the evil, but God already has a system that takes care of injustice. Sometimes we think that we must tell others about our good deeds, but God already has a system to rewards the benevolent. Understanding causality reveals why we suffer or have joy.