Great question: check out this answer from a 7-year-old:
http://www.patheos.com/blogs/naturalwonderers/not-caring/?utm_source=SilverpopMailing&utm_medium=email&utm_campaign=Atheist%2009%2030%2015%20%281%29&utm_content=&spMailingID=49669493&spUserID=NTExMjEzNzE3NzkS1&spJobID=780104491&spReportId=NzgwMTA0NDkxS0
http://www.patheos.com/blogs/naturalwonderers/not-caring/?utm_source=SilverpopMailing&utm_medium=email&utm_campaign=Atheist%2009%2030%2015%20%281%29&utm_content=&spMailingID=49669493&spUserID=NTExMjEzNzE3NzkS1&spJobID=780104491&spReportId=NzgwMTA0NDkxS0