The argument against God on the basis of the existence of evil

An Agnostic Argument based on Epicurus – Faith & Life.

The problem is that the premises can always be changed around. To wit:

1. If a perfectly good god exists, then there is no evil in the world unless he has some morally sufficient reason for permitting that evil.
2. There is evil in the world.
3. A perfectly good god does exist.
   
4. Therefore, there is a morally sufficient reason for that god permitting the evil in the world.

The atheologian has to prove that there can be no such morally sufficient reason. But how can he prove this? It would be a universal negative and claim to know all the possibilities that a god would have to account for.

hat tip