In about 300 B.C., Epicurus eloquently summed up the problem of the existence of evil. It has come to be known as the Riddle of Epicurus or the Epicurean paradox. It was translated by David Hume in the Dialogues concerning Natural Religion:

If God is willing to prevent evil, but is not able to

Then He is not omnipotent.

If He is able, but not willing

Then He is malevolent.

If He is both able and willing

Then whence cometh evil?

If He is neither able nor willing

Then why call Him God?