.... since everybody REALLY, deep down inside, knows heaven & hell are made up stories (yeah, veryly, even fundies!), condemning atheists to a torment that everyone knows will not happen is not as bad a saying "fuck you".
That's how you can give as good as you get from them. Just smile and say "You know it's a fairytale. You KNOW it."
I'm sorry, but it takes SO MUCH ENERGY for fundies to keep up their "faith". You know when they're lying in bed, staring at the ceiling, waiting to fall asleep, it occurs to them, however briefly, that it's all BS.
For me, being an atheist has never been any kind of effort. I've always been this way, even when I was expected to go to church (which I did to make others happy... and not get demerits at prep-school). I even played with Tarot cards, but to tell the truth, I was more interested in the occult-y artwork and their history than thinking they actually did anything. But now, I just use no energy at all trying to remain atheist. Just look at the energy and $$$$ religion spends keeping reality at bay! I don't worry about anything supernatural. Reality is enough for me... and it's amazing! And science tells me in the most concrete sense that I am made from the cosmos, and related directly to everyone else, and whatever I do, no matter how insignificant to my culture, it will make a huge difference eventually. These things are so concrete, you can back them up with evidence. There's no need for me to force Stone Age myths into relevancy. That effort is just too great and unrewarding. All I have to do is look around at a world without supernatural anything and know I'm literally part of it.