Optimatally, Luthor's a total foil to Superman, and one of the best hero-villain foil dynamics in all of comicdom.
The simplest bit being power, and their concepts of it and the idea of right: Superman has great alien powers and abilities, but does not see himself as any greater than humanity. Luthor has obtained great economic and political power with the help of his very human genius, and sees himself as superior to the common man. Luthor's ego extends greatly to his worldview - he sees that the optimal being should be his mirror. As he is the superior example of man, the uberman should have his virtues and share his flaws - perhaps extending to the idea that all people are intrinsically like him.
So when Superman comes along with power rivaling if not surpassing his own, but none of his arrogance and greedy ambition, Lex immediately takes outrage with the very concept of him.
While Superman is genuinely altruistic and is dedicated to doing good, Luthor's stints of altruism are all rooted in ego somewhere - while he genuinely believes
a lot of the bile he says about Superman being a blight to humanity, it's merely him believing the lies he constructed to cover a mix of Evil Cannot Comprehend Good
and It's All About Me
(as again, he feels that should the world be brought to utopia it should be done according to his
As he is, Luthor isn't an antagonist because he dislikes and hates Superman, he hates Superman because his very character causes him to be antagonistic to what Supes is and stands for.
edited 4th Oct '12 10:46:51 PM by KnownUnknown
"My final prayer: O my body, always make me a man who questions!" — Frantz Fanon