“ Gods were created for societies to prosper? What evidence is there to show such a hypothesis?”

There is some evidence that points to the importance of creating a god, for example from psychology and sociology research:

http://www.nature.com/nature/journal/v530/n7590/full/nature16980.html

I tried to expand on this evidence in part 1 of the series. In a nutshell, the belief in god can be understood as a powerful hierarchical shared belief system; and having a system like that was necessary to make the advancement from small tribes to much more complex societies.