Such a threat has about as much meaning to me as if they'd exclaimed "bopity bop plobalop wibble wobble woo", although slightly less amusing.

I generally just shrug and ignore, unless in the mood to have a lengthy and tiring debate where I request objective evidence for the claim and then have to exhaust myself explaining how citing a religious text as proof of it's own accuracy is a circular argument and not an objective one.

"Demons, sodomy, and so much heat the clothes are likely to come off. Doesn't sound too bad to me."

Ok, see you soon.

If Pope Francis says I can get into heaven as an athiest, just trying to do good and living by my own moral code, then that's good enough for me. As a Catholic, I would be expected to repress my sexuality. As an atheist, I don't have to.

And the scoreboard says:
Atheism 1 - 0 Catholicism

Sad that their religion is based on reward and punishment. The only hell is theirs.

"if you dig a pit for someone, you end up in it yourself"

I just laugh. I can't say it won't happen but doubt it so strongly as to ridicule this God of theirs. I tell them that I hope to actually have that Judgment Day so I can look Thou in the eye and ask what kind of sick motherfucker Thou is? Was the experience I just had to endure really necessary or some kind of uncomfortable joke? That usually shuts them down but gets a horrified chuckle.

Surely the only valid response is laughter?

I tell them I am a New Thought Christian(which I am) and so I don't believe in Hell. Further the Hell they believe in was invented during the Dark Ages by Dante. Jesus wouldn't have know what they were talking about. If that didn't work, I would probably beat them over the head with the very scripture they tried to attack me with. (Metaphorically of course). A good New Thought Christian would never do this, so I guess I have a ways to go.

Hah, that puts them on the ignore list immediately.

See you there. Then laugh maniacally

How am I supposed to take the threat of hell seriously when I fundamentally don't believe in it? It is a specious threat. I suppose my response is "oh."

I would just laugh at them and tell them you will be sent to the North Pole because I would rather be hot than cold.

I tell them, “Sorry, Satan already offered me a job in Human Resources!” “Now run along, I’ll see you later.” With a devious smile.

I say " you wanna get butt naked and wrestle?"

Laugh.
Maybe say, well all my friends will be there, if they tell me I am going to Hell.

That has never happened to me. Ever.

I get all choked up and say "I'm Sooooooo scared"

I laugh at them & tell them that their ridiculous delusions have no affect on life (or after life, for that matter).

Ask them why they think anyone would want to spend eternity with someone like them. That usually quiets them down.

I think it's funny, I don't believe in those things.

I saw a bumper sticker once with the perfect response. It said, “It’s your hell, YOU burn in it.” Cracked me up.

Laughter, usually.

simple: I say: "They tell me that Hell is a lot like South Dakota only the weather is better.

The Hel or Hella myth ( Loki's Daughter ) was that she took in the unworthy. The expression " go to Hella was originally "go to Hella" It meant that a person was so worthless than nobody else would take their spirit. I have one friend that refers to Evangelicals as Hella's Army.

(Threat): You will burn in hell!
(Response): Then so be it, see you there. (smile)