To understand the argument, we need to be clear on what ‘evil’ means in this context. ‘Evil’ usually refers to morally wrong actions or motives of human beings. So we say that Hitler was evil in trying to eradicate the Jews or that ethnic cleansing is an evil policy. This is ‘moral evil’.
But this isn’t the only kind of evil the problem of evil is talking about. There is also ‘natural evil’, which refers to suffering caused by natural events and processes, e.g. the suffering caused by earthquakes, illness, the predation of animals on each other, and so on.
The two types of evil are distinct. What people choose to do to each other is not usually the result of natural events. Sometimes it is: famine may drive people to stealing and killing; but this is the exception. And natural events are not usually the result of what people choose to do. Again, sometimes they are – the results of global warming could be an example. But nothing people did caused the tsunami in the Indian Ocean on 26 December 2004 (which killed hundreds of thousands of people).
We need to keep both types of evil in mind when we look at responses to the problem of evil. In particular, some responses may solve the problem of moral evil, but don’t answer the problem of natural evil.