It always bugs me that fundamentalists think there would be no morality, and life would have no meaning without a belief in god. They honestly believe that morality was delivered to Moses on the mountaintop. Before that, I guess, people were just running around doing anything they wanted, because they didn't know it was wrong to lie, cheat, steal, kill, or covet your neighbor's wife. People from other cultures who coexisted with the Jews obviously had no moral code, either, and their lives had no meaning at all. I guess that's why god want the Jews to kill every last one of the men when they invaded their land, and take the women and children as their slaves. When they didn't do this properly, god punished them! (I should provide a refernce here, but I am to lazy to go look it up. Maybe one of my followers can help)
I think the ten commandments encoded morality as it had developed up to that time. People developed this themselves over time, by trial and error. Conscience evolved as our societies did. People who want to stop the clock at the time the ten commandments were written down deny that our morality and conscience could possibly evolve over time. So what was wrong then (read:homosexuality) is wrong now. And what was right then (read: slavery, genocide, polygyny) is still right today. Oh, wait...
As far as the meaning of life goes, I don't think life has any meaning in and of itself. Saying life has some inherent meaning is like saying that the sounds of our language have inherent meaning. They don't. But in context, in a society that has assigned meaning to the sounds and gestures, it means a whole lot. Live is like that, too. Your life means nothing to the earth. The earth was here before you and will go on after you are gone. The earth may very well swallow you up in a gigantic sinkhole tomorrow, and it wouldn't be anything personal. The stars in the heavens don't give a hoot for your life. Neither do the comets and asteroids which bombard us from time to time. But in context, from you point of view, and from the point of view of others whom you affect, it means a whole lot. What you leave behind has meaning too, as long as there is someone who understands. In a few thousand years, no one will understand the language we use today. There may be some who study ancient languages who can decipher it. Society will be so different from what it is like now, that they may not have the context to truly understand the way we thought, and why we did the things we did. Maybe they'll judge us by their own standards and find us lacking. Maybe there will be sects who look back at our moral code and deplore the morals of their own society! Who knows? It's happened before!