Dystheism (from Greek δυσ- dys-, "bad" and θεός theos, "god") is the belief that a god is not wholly good and can even be considered evil. Definitions of the term somewhat vary, with one author defining it as "where God decides to become malevolent". The broad theme of dystheism has existed for millennia, as shown by trickster gods found in ethnic religions and by the view of other representations of what the various belief systems regard as the Supreme Being, such as the creator deity as conceived in Abrahamic religions, through a non-religious lens as angry, vengeful, smiting, and hypocritical. The modern concept dates back many decades, with the Victorian era figure Algernon Charles Swinburne writing in his work Anactoria about the ancient Greek poet Sappho and her lover Anactoria in explicitly dystheistic imagery that includes cannibalism and sadomasochism.
The concept has been used frequently in popular culture and is a part of several religious traditions in the world. Trickster gods found in ethnic religions often have a dystheistic nature. One example is Eshu, a trickster god from Yoruba mythology who deliberately fostered violence between groups of people for his own amusement, saying that "causing strife is my greatest joy." Another example is the Norse Loki, though Odin has these qualities as well. Zoroastrianism involves belief in an ongoing struggle between a creator god of goodness (Ahura Mazda) and a destroying god of hatred (Angra Mainyu), neither of which is omnipotent, which is a form of dualistic cosmology. The ancient Greek god Ares, depending on time and region, was associated with all the horrors of war.
Dystheists may themselves be theists or atheists, and in the case of either, concerning the nature of the Abrahamic god, will assert that God is not good, and is possibly, although not necessarily, malevolent, particularly (but not exclusively) to those who do not wish to follow any of the Abrahamic religions.