They really don't unless they're strangers, but if they do it's usually met with humor & sarcasm.
If there is a God and he doesn't understand why I don't believe than he is not the God they talk about.
this would depend on whom was making the threat, but generally I would simply ignore it or make a sarcastic comment in return
and I presume Santa Clause is going to give me coal for Christmas this year also? Tell your imaginary friend that he's kind of a jerk and nobody deserves to be tortured for all of eternity.
Usually laugh a bit.. and explain that it's the equivalent of me threatening them with the actions of voldemort, or the orc horde.. I then usually explain, that if their god is real.. I wouldn't want to spend any time with the narcissistic mass murder, and will enjoy the company of any alternative.
The notion of "Hell" being a place of Flaming Brimstone is exceedingly silly. Once the physical body dies we no longer have nerve endings to experience such physical pain. It's a "marketing ploy" to scare people into believing their BS. It's fun to give them pure logic to disagree with them. They get all dumbfounded and start repeating themselves since they have no REAL responses to intelligence.
May you burn in hell ? my reply " What makes you think I'm not already there ? "
I have an expressive face. Do not need to say anything, give them 'the look'
I always say “good, that’s where all the awesome people will be.”