God, Religion and Selfishness

The other day I was discussing about God/Religion with my theist friend. He was arguing that if every one become atheists the World will become a very Selfish World.
Is that correct? Is the World or the Organisms residing in the World not selfish (or less selfish) because of their Beliefs in supernatural God?
I do not think so.
Doing good things to others just because you are afraid of ‘God”s punishment and to attain ‘heaven ‘ can be considered as one of the most selfish of all acts.
But still some people will say even if done for a selfish purpose, it is good.
I agree that people doing good things to others is good. But is it really because of God/religion? Is it because of unselfishness?
Non believers also do good things to others. What is the explanation for their noble acts?

In my opinion all living organisms in this World are selfish. All of them are seeking their own happiness. Happiness is a certain state of our Brain. We try to attain that state constantly.When we reach that state we automatically try to share our mood with others. Our body is hard wired to share ( or let others know) our emotions. That is why we smile/laugh when we are happy and cry when we are sad. Other wise there is no purpose for smile/tears.
When some one smile or laugh in front of you, automatically you tend to smile or laugh. Mirror neurones in our Brain are responsible for this behaviour. Thus happiness becomes infectious. Sorrow is also infectious like this.
When we help others we are trying to make others happy (smile/laugh). Their happiness in turn make us happy. So the primary purpose of doing good things to others is to make us happy, a very selfish motive.
This selfishness is a very good thing and has nothing to do with God/religion.