Conflict between good and evil

The conflict between good and evil is one of the precepts of the Zoroastrian faith, first enshrined by Zarathustra over 3000 years ago. It is also one of the most common conventional themes in literature, and is sometimes considered to be a universal part of the human condition. There are several variations on this conflict, one being the battle between individuals or ideologies, with one side Good, the other Evil. Another variation is the inner struggle in characters (and by extension, humans in reality) between good and evil. Conrad defined all humans as having an "inner evil" or Heart of Darkness in his novella of the same name.

https://en.wikipedia.org/wiki/Conflict_between_good_and_evil