"Of course," replied the atheist. "If little spheres need causes, then so do larger ones."
"Ah, so," said the theist, "then what if it were eight thousand miles in diameter-would it still need a cause?"
The atheist paused and said, "Yes, if little spheres need causes and larger ones do too, then a really big one would also need a cause."
Then the theist said, "What if we make a ball as big as the whole universe: would it still need a cause?"
"Of course not," snapped the atheist. "The universe is just there!" 
Courage and Godspeed,
1. Norman Geisler, If God, Why Evil?, p. 15.