So, my religious neighbour asked me out to lunch last week and I went, with the stipulation that we don't talk about religion and we did it!
The next day, she called me because she was upset and needed someone to talk to who was not "judgemental". Then when I am telling her that sometimes people make mistakes etc. she throws out that She doesn't know why she called me because no matter how good a person I am I am going to hell because I don't believe in Jesus.
So I asked her why she didn't call one of her christian friends and she said because I was easy to talk to and didn't judge.
I asked her why she felt she could judge me, if she didn't want to be judged. She said nothing and I said goodbye.
I know she will call me again ( she always does)
What would you do? Talk, or tell her you were busy or would you say something else?
Point out that until you go to hell, you will continue be that good person she has discovered until you die.
Therefore, in this real world, you are acquitted of all charges.
Later, ask her if she believes that devout Samkhya Hindus will go to hell? If she thinks they will be "saved", point out that they have no belief in a god. If she thinks they will be damned, ask her if she approves of yoga, which they invented.
Either way, it should help her to start questioning her ingrained beliefs.
Are you enjoying the friendship or are you just trying to be diplomatic with a neighbor? If she's more of an annoyance to you, I would just make myself less available If on the other hand, if you're enjoying your pointing out the inconsistencies in her belief system, then it's up to you whether you want to continue.
How important is it to feel needed by her? ... I remember once a guy called me an asshole, not on religious but on ideological grounds. I asked him whether would rescind from this insult. "NO" he said emphatically. "Great," I replied, so I don't have to pretend to respect you.
Why don't you challenge her on the specifics of hell? Temperatures range, fuel type and consumption etc. and what materials are being used to insulate Heaven from Hell.
Knowing only what I read into your post, you showed her kindness even when she attacked you. This is what a true Christian SHOULD do but obviously she is not getting this from her christian peers. In my opinion, continue to be kind and walk away when she turns on you. If she doesn't come to see what she is doing, walk away and rest easy.
Telling an atheist they will go to hell is about as scary as a warning about the possibility of being gored to death by unicorns. Take a light hearted approach to any of her outbursts, walk away laughing & shaking your head, & she may get the message that she's wasting her time telling you fairy stories. If not, she doesn't deserve your friendship.