The fictional "God" character cannot be cross examined because he is fictional, like the "late great Hannibal Lector"
"God" is invisible, intangible, tasteless, odorless and mute. Such a being cannot be cross examined.
Of course, he is also fictional. Might as well try to execute the "late great Hannibal Lector"
But now we know what sort of execution Trump fears. Stuff him in a bathtub, plug in a DeLuxe four slice Proctor Silex toaster and fling it in. He likes to threaten people, perhaps a specific threat might make him STFU.
After that, he could be thrown to a shark, perhaps. But I am partial to a grave with the urinal combo feature.