By The Rev'd Lloyd Prator Books and books have been written on this, which is probably the most frequently asked question about Christian faith, by Christians and non-Christians alike. Let us take a moment and try to understand what is behind this difficult question. There are two kinds of evil. Volitional evil and natural evil.
Natural evil is the sort like hurricanes, epidemics, plagues, and the like.
That kind of thing. Both must be tolerated in order for freedom to have any meaning at all. If God were to step in and set aside every hurricane and every virus which plagues us, pretty soon the natural world would lose its predictability and we would be unable to rely upon an orderly nature. The same law of gravity both pulls a fully loaded airplane down from the sky, killing 300 people, and, at the same time, enables us to drive ambulances along roadways to bring people to medical care. Evil is a result of consistent created order.