Drill Sergeant: Gump! What's your sole purpose in this army?
Forrest Gump: To do whatever you tell me, drill sergeant!
Drill Sergeant: God damn it, Gump! You're a goddamn genius! That is the most outstanding answer I have ever heard. You must have a goddamn I.Q. of 160. You are goddamn gifted, Private Gump.
If we're here as a result of a series of improbable events with no divine hand behind it all, then life has no meaning.
That's what theists like to tell me, anyway.
But what is the meaning of life if God exists?
To serve God.
No thanks. God doesn't need service and I'd rather fly a kite.
To go to Heaven.
Heaven seems awfully boring, unless we're talking about the Muslim Heaven. But I don't see how that would be more meaningful than, for example, trying to have sex with 70 virgins here on Earth. (Why virgins, though? I think I'd get sick of newbies.)
To become one with God.
Sophisticated theists have redefined the whole Heaven thing because the original version was too silly. Now it's all about becoming one with God or something. Eh. That doesn't seem so meaningful either. Why don't I just become one with my couch?
To be a living expression of God's greatness.
Okay, God's going through His angsty adolescence and wants to express Himself all of the sudden. If I wanted to play a part for some frustrated megalomaniac, I'd join the local theater.
Tikkun Olam. To bring the world to a state of peace and harmony where the world can live as one, with much singing and frolicking.
That would be just as meaningful without God. Besides, He's the one who kicked us out of the goddamn garden in the first place.
Edit: Apparently I totally stole this post from Bacon Eating Atheist Jew!