If there is no god..then why did man invent him?

The idea of god or god(s)/goddess(es) served many functions. Prescientific people were still curious and wondering. They looked about at nature and wondered how things worked. Lacking the ability to investigate the ways we have since developed and being imaginative they wove stories. As oral cultures that sat about fires without tvs, ipods, stereos, etc.. they told these stories to each other. The stories also wove aspects of their cultural identity into them and the rules that the societies structured themselves on. Another big factor was the idea of an after life and the comfort that idea gave people against their fear of mortality and loss of loved ones.