So god is the same as the most selfish and greedy within society?

Also that does not hold up thousands of years ago when the world was not always as conneted or able to produce surplus crops. Even nowdays we lack the medical knowledge to cure many diesase or conditions.

Still coming from a fictional character who drowned everyone on earth including numerous children because they did not meet his standards one would expect such a selfish answer.

I would ask them where they come from

To God: "Can I take over for you whenever you're done?"

To Lucifer: "Why you letting God kick your ass? Don't let him walk all over you, go over there and show him who's boss!"

I would ask them where they bought such convincing costumes from.

I would ask which one of them I should punch in the face for creating Miley Cyrus.

God: Why do you have long hair and beard? Are you a metalhead?
Lucifer: Why are you red? You weren't red before falling.
Both: Why are you so selfish and won't let us see you so people will stop arguing about who exists and who doesn't?

God: How do you know you aren't a creation yourself? Maybe everything you know was actually artificially implanted in your mind. How can you tell the difference?

Lucifer: Have you thought about repenting for your sins?

A simple "Why?"

I'd ask them which one would let me listen to Metallica for all eternity 'cause that's the one I'll choose for the afterlife. Don't want to be doomed to shitty music, better make sure.

Do you mesn like spanking a kid after they did something wrong as punishing? And i guess the knowledge would be limited to everything that they both individually know.