The following quote is wrongly attributed to Epicurus, an ancient Greek philosopher:
“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 whence cometh evil? Is he neither able nor willing? Then why call him God?”
The “Epicurean paradox” is a version of the problem of evil. It is a trilemma argument (God is omnipotent, God is good, but Evil exists), a type of argument which was favored by the ancient Greek skeptics, and this argument may have been wrongly attributed to Epicurus by Lactantius, who, from his Christian perspective, regarded Epicurus as an atheist.
According to Reinhold F. Glei, it is settled that the argument of theodicy is from an academical source which is not only not epicurean, but actually anti-epicurean. The earliest extant version of this trilemma appears in the writings of the skeptic Sextus Empiricus.
Epicurus didn’t deny the existence of gods. Instead, he stated that what gods there may be do not concern themselves with us, and thus would not seek to punish us either in this or any other life.