An interesting fact regarding this riddle: They told this riddle to a group of kindergartners and a group of Stanford students. 80% of the kindergartners solved the riddle within 2 minutes. 80% of the Stanford students NEVER FIGURED IT OUT!!! 

Hint: Try to think on the level of a kindergartner. 
 
 

ANSWER: NOTHING. 

NOTHING is greater than God,
NOTHING is more evil than the Devil,
the poor have NOTHING,
the rich need NOTHING,
if you eat NOTHING, you'll die!