If we are to understand the problem of evil, we must apprehend its form.
The problem of evil goes something like this:
God is Omnibenevolent (all-good)
God is Omnipotent (all-powerful)
If you maintain any three of the above propositions, the rejection of the fourth is insinuated. (This is how the problem of evil is put to the Theist)
In other words:
If God exists, wills all-good, and is powerful enough to get everything he wills, then there would be no evil.
Or, if God exists and wills only good, but evil exists, then God does not get what he wills. Thus he is not all-powerful.
Or, if God exists and is all-powerful and evil exists too, then God wills evil to exist. Thus he is not all-good.
Finally, if “God” means ” a being who is both all-good and all-powerful,” and nevertheless evil exists, then such a God does not exist.