"Problem of Evil"
Is God willing to prevent evil, but not able? Then he is not omnipotent.
Is he able, but not willing? Then he is malevolent.
Is he both able and willing? Then why is there evil?
Is he neither able nor willing? Then why call him God?

Apparently Epicurus (and other Greek philosophers) felt that if God is good, and omnipotent, then He is obliged to stop or prevent evil.

If God desired a world without evil, He could have created one. Since God created a world in which evil is present, a world without evil was not a part of the plan.

One of the side effects would be that we would not have free will. We could have a small, inconsequential, free will, such that we could select the color of the shirt we wear today.