| In Euripides play, "The Bacchae," Dionysus, the god of wine, madness, and revelry, vows to avenge the slandering of his dead mother by her sisters and the disbelief in his godhood by proving that he truly is a god, and that he truly is powerful - not just an imposter.
After the spirit of Dionysus infects the women of Thebes, (including the aunts who were slandering Dionysus' mother by claiming that she did not bear the child of Zeus, but of some mortal man - using Zeus only as a means to save face) they go on an orgiastic rampage, hunting and ripping apart live animals with their bare hands.
During this frenzy of religious ecstasy, Dionysus' aunt, Agave, rent the body of her son, Pentheus, the King of Thebes, and returned to the city carrying his severed head. All the while, Agave believed herself to be killing and subsequently carrying the head of a young male lion. Once she was before all of Thebes with her son's severed head in hand, the hold that Dionysus had over Agave was broken and she realized what she had done.
This play is a perfect example of the reasons not to annoy or anger a god, particularly one as powerful as Dionysus, whom Euripides placed on equal level with Demeter, goddess of earth and growing things. I do not, per se, believe that Dionysus did the "right thing" in a moral sense, but human morality rarely, if ever, applies to gods. Dionysus, as a powerful god who was being denied his proper rites and worship, took the measures he saw fit to demonstrate exactly why the people of Thebes should worship and revere him. For a god, that is a perfectly acceptable and valid reason for having a king slaughtered by his mother's bare hands, even if it does seem a bit extreme to mortals. | 
