What was his motivation in the movie exactly?

First he appears to despise superman as some kind of false god and wants to use a mortal (batman) to kill him in order to disprove his divinity.

That or he likens him to a potential dictator, the likes of which his abusive East German dad had to salute when young.

Later he creates Doomsday to kill supes (so why rope in batman in the first place?), if doomsday was seriously powerful enough to kill superman and batman then it's safe to say he could wipe out the planet. So Lex basically was willing to kill off the planet just to get supes.

And at the end of the movie it's implied he has invited Darkseid to come to Earth.

Did he just want to watch the world burn /co/?