A bit over a year ago, my mother died. My father died a few years ago (2005) as well.
For one, I was "kinda-sorta" spiritual. For the other, I was an atheist.
Now, most religious people will understand how they deal with death. The idea of the passed one going on to "a better place," they're at peace or "with God" (or whatever deity they believe in.) I don't have to explain to them, I think, how they feel.
There is, typically, a community "by default" they can go to and rely on for support, even for those with no other family - namely, their church, mosque, temple or what have you. And, with few exceptions, I do actually find this to be a good thing for most religious people - generally without someone preaching at them, at least. It's another place to go for the emotional balm and healing needed at that time.
But what about the Atheist?
This is a legitimate question asked by the religion - what does the atheist do in times of hardship and loss? Now, some - not all, by any means - are going to basically say "who cares, they deserve it," and those people need to be brought down a few pegs by their fellow believers, quite honestly. An atheist doesn't, by definition, have a church or the community that goes with it.
And an atheist doesn't believe, of course, that the dead person has gone to heaven to play guitar with the angels or play a piano trio with Mozart and Liberace.
For the atheist, we have one life. There's no soul that's been proven or even given reason to suspect exists. There's no heaven. Of course, that also means there's no hell, which can be a source of worry for the religious ("He never accepted our beliefs, now he'll be tortured for eternity" doesn't help ease the pain of someone in mourning.) When we die, we die, and the elements that make up our bodies are returned to the environment.
So, sure, for the atheist, we can define the afterlife - After life, we are fertilizer. Which isn't a bad thing (I want to be buried with a tree nearby, preferably overlooking the lake.)
Still, how do we deal with death? Just like the religious person, it varies from person to person. For me, I missed my mom (my most recent loss,) but it was easy for me after a bit to accept she was gone. I can't say honestly that it WAS my atheism that helped with a - stopping point, I suppose - or if it was just having been through it before with my dad, or me being there helping her through her last years.
I do know that, for me, it helped me strip away all the religious trappings, the "she's getting her reward" (with the question, then, "if she was so good, why didn't she deserve better here?") and the like. I do also have a fairly good size family, three brothers, a sister, and all their kids, spouses and whatnot. Part of my energy went to comforting them. And part of it went to preparing the house for sale and moving.
But all that can also be called avoidance, too. Which isn't bad - you shouldn't focus, after all, on just "that person is gone, I miss them!" Nor should you feel guilty when, eventually, you realize you don't hurt like you did when they passed.
Still, rationality helped me. I couldn't say she died young - she lived to her mid 70s, so she'd had a good, long life. She set a wonderful example, for the most part, for our family. She was a loving mother, even when we argued. She had given to the community, she was willing to give of herself. And, of course, I had been there as she fought cancer - twice. And at the end, I saw her give herself over to the inevitable, prepare and accept what was coming, and knew she was not going to be frustrated by weakness, by what the cancer was doing to things like her memory and brain, and what she might feel she was losing.
In the end, it WAS an end - and a fast one, and the closing of the chapters of her life. And as I thought about her and her life, I couldn't help but feel good and satisfied for her. She probably had things left she wanted to do, sure. I know she did. But her loss wasn't early, and it wasn't sad, and I could take comfort in everything she had done and the legacy she had left for us.
That's the only end this Atheist can talk about. I haven't lost anyone to war or tragedy, and can only think it would make it harder. But even if I had - I could only talk about my own. The only advice I could give, which I hold true for both atheist and believer, is not to dwell. Put the energy into something else - if it's doing something for the sake of doing something, or doing something the loved one you've lost would have approved of, or doing something "in memory of" that person, the energy can be put to better use than reinforcing your mourning.
The other thing? In this Internet-connected age... you're never alone. You don't have to be. You can usually think of someone - a person or group - who means something to you. Don't be afraid to open up... it helps.
That's how this atheist deals with death.