Unless J is much, much less intelligent than you, or you've spent a lot of time planning different scenarios, it seems like any one of J's answers might well require too much thought for a quick response. For example,

tld: Well, God was there, and now he's left that world behind. So it's a world without God - what changes, what would be different about the world if God weren't in it?
J: I can't imagine a world without God in it.

Lots of theists might answer this in a much more specific fashion. "Well, I suppose the world would cease to exist, wouldn't it?", "Anything could happen, since God wouldn't be holding it together anymore!", or "People would all turn evil immediately, since God is the source of conscience." all seem like plausible responses. "I can't imagine a world without God in it" might literally be true, but even if it is, J's response might be something entirely different, or even something that isn't really even a response to the question (try writing down a real-life conversation some time, without cleaning it up into what was really meant. People you know probably very often say things that are both surprising and utterly pointless).