Lots of religious people are really confused about atheists be because they're like "aaa how can you feel like there's a point to anything if you're just going to stop existing someday." So they wonder things like, why would an atheist write a book? Someday they will stop existing and the book will not matter. Or like, why would they learn to dance? Someday they will not exist and so dancing will not exist for them.
So one thing is that that's why a lot of people like to leave something behind. Like, even if they stop existing, their kids will keep existing, and their name in a history book will keep existing, and the people talking about how awesome they were will keep existing.
Only, that doesn't totally work either, because why do you care about other things existing if you're not going to exist anymore?
So the other thing is that you do exist right now, and if all goes well you're going to keep existing for a pretty long time. So, you could go "oh, well, I'm going to stop existing one day, so I guess I won't learn to ride a bike." But that's a long time of existing without being able to ride a bike. Like, let's say a person can learn to ride a bike when they're ten. If they live to be like seventy, which is pretty good, they lived for sixty years with no bike. And that time is going to be pretty sad because they like biking.
Or like, I'm planning to write books regardless of whether or not the afterlife is a thing, because writing makes me happy now. Right now I exist, and I'm basically incapable of going "well I'm going to stop existing someday so I guess I'll just be miserable for a really long time." Being miserable sucks and you can't just let yourself be miserable forever so you do things to change that even if one day those things will go away for you.
It's similar to people who go "well, I am never going to sing professionally, so I will not take singing classes." Well, no, maybe you won't be a professional singer, but isn't having fun singing pretty excellent? If it's more fun when you know how, that seems like a pretty good deal even if people don't throw money at you for it. I don't expect to get any money or anything from writing web pages or Flash games, but it's enjoyable right now, so why not? Or like, lots of people don't expect to get money from watching television or playing video games, but they do that anyway, because they like it. You could say "well, you can learn things from tv!" or "but I'm accomplishing something in my video game, look, I got a new highscore!" and that's great for you, only, you'd still do it even if you couldn't learn or get a better score, because it's fun.
You'll notice this, too, in media where someone's about to die. They want to go skydiving, and scuba diving, and they want to confess their undying love to the person they like... and no one watching these scenes thinks it's strange, because it isn't strange! It's basically human nature to want to enjoy yourself even if you're going to die or even if you're not going to get any money. These people aren't going "aaa I have to skydive quick so I can get into the afterlife", they're just having fun.
Things don't have to get you any tangible benefit to be worth doing! You can sing because it's enjoyable rather than because you're getting payed, you can run to feel the wind in your hair rather than to lose weight, you can read a book because it's really good rather than because it teaches you something. And you can be a good person and try your best because it feels good and it makes others feel good rather than because the afterlife will be nicer if you do.
I tend to subscribe to the idea that the point of life is to do your best, because that's what feels the best to do. And it feels good even if I don't get money or a good afterlife from it.
I'm going to be around way too long to not try my best, and to not do things that make me or others happy when I can, so it seems better if I do those things.
I think some other people give life some other purposes, like "leave your mark on the world" or "make God happy so that eternity won't be in a scary fire place", but I don't like those ones as much.
Trying your best is pretty much always a good thing, and you should do it regardless of whether or not God or a potential employer is looking over your back and regardless of whether or not you'll exist forever.
