Most atheists recognize the fact that there just is no greater meaning, intrinsic value or purpose to our existence nor is there some ultimate goal or justice for that matter. Theists use this observation as some kind of argument for god. It goes something like this: “It’s really depressing to think that there is no meaning to this life, and we just die. Therefore, God exists because that sounds better, and it makes me happier.” They may not say it just like that but that’s generally what they are implying.
Truthfully, humans ascribe whatever meaning they want to this life. The fun thing about being an atheist is that we can tweak it and change the meaning we ascribe to it as we mature and life circumstances change. We aren’t stuck with the idea that we are solely meant to pronounce the love of god to the world and try to get to heaven, with all the cognitive dissonance to go along with it. Life is more sophisticated than that and far more adventurous.
Some of us find meaning in chasing the almighty dollar despite the ill-affects it has on health and relationships. Apparently, Steve Jobs took this route and ignored his children entirely, only explaining his intentions postmortem. Some of us find meaning in traveling the world and learning from different cultures. Some of us find meaning in providing for our family but spending quality time with them as well. It doesn’t mean that a person can’t change what is meaningful as life goes on. In the end, they may recognize that they put their career in front of their children and change what’s meaningful toward their relationship with their children. I personally find more meaning and fulfillment in relationships, enjoyable hobbies, writing, reading and playing than I do in working 80 hours a week but that’s just me. I've never had a materialistic obsession. I say you should do what makes you happy as long as you aren’t hurting others or yourself.
The point is that it’s your life to live. You don’t need or want a book to tell you how to live it, or what should be important to you. You can decide what matters the most, what makes you happiest and what you wish to avoid. I find that far more appealing then living under a dictator who threatens you with fire and brimstone if you fail to live as he commands. You're robbing yourself from what life has to offer when you allow someone else, fictitious or not, to tell you how to live it.