Problem of evil
From Epicurus Wiki
Epicurus is generally credited with first expounding the problem of evil. It also referred to as "the riddle of Epicurus" or "the Epicurean paradox." Epicurus is said to have argued that the existence of evil is incompatible with the existence of gods who are completely aware of, interested in, and able to remedy the plights of mortal beings. The original written source of Epicurus' argument is lost to us; all we have to go by is how Lactantius, a hostile Christian critic, rephrases Epicurus' argument (which we cannot take to be direct quote, given the monotheistic tone) which goes like this:
Either God wants to abolish evil, and cannot; or he can, but does not want to. If he wants to, but cannot, he is impotent. If he can, but does not want to, he is wicked. If God can abolish evil, and God really wants to do it, why is there evil in the world?