From the beginning, life has been about survival and reproducing before dying.   Altruism evolves where there is a greater possibility of individual life or perpetuation of a species by living within groups.  Schools of fish sacrifice a few when a predator is around, but the probability of a single fish, itself, dying, lessons.  Obviously, humans coming together has great rewards for shared knowledge, shared resources, better access to food and shelter, protection if attacked. availability of health care for the long term or in emergencies and the list goes on from there.   We made laws as we came together to protect the safety and welfare of each person by protecting the society at large and to govern the production and distribution of food and resources.   It seems like this should be sufficient to protect altruism as a whole.  So why did every culture of man, create a Supreme Being, a god or gods?  

Definitely man (with his ever questioning mind) sought to explain from where he came: to understand why he existed.  Those questions accompanied an evolving brain that allowed him to ask questions and seek the answers.   The ability for an organism to learn is related to the benefit of learning  in its evolutionary past and the complexity or variability of its environment which requires the ability to change and gain knowledge, especially in species with long life spans.  When I think of the universe, despite myself, I think from where did it come? , and if I think of an answer to that, then my mind questions where did what it came from,  come from and that can go on forever. The same applies to God.  If God created the universe and man, where did God come from?  So although giving explanation in the short term, Man was created by God or gods, it does not answer from where God came from or why.  Yet, still, every culture had a god or gods and a story of how mankind and the earth came to be. 

Along with the stories of creation and the manifestation of a god(s), came the litany of behavioral rules upon which society was to conduct itself as an individual and as a whole and how to appropriately honor the god that created them.  The idea of a sacrifice and giving to the unseen god goods and lives honored the gods by giving to that deity something that was of extreme value to the individual,culture or society.  I imagine that since life itself was such a mystery, thinking that a god created us, made us feel that same god could kill us or provide us with feast or famine.  I can see man beginning to deeply revere this unseen source of life.  With that worshiping fever, came the ability to use religion and gods to control mans behavior and to control groups of people more easily.  

Creating a god or gods gave man a sense of beginning, gave enormous power to the god or gods, and created a hell where people who did not obey the laws of that god or gods ended up after death.  It relieved man's fear of death by creating an after death life which was not final.  The general laws of every religion are basically the same: do not kill, do not steal, do not lie, do not commit adultery, do not bear false witness and so on.  Those are the same laws which man needed to survive and function as a group.  As such, why did we create gods to provide those laws?  So then comes the question: if mankind had not created religion or a god(s), would he have evolved in the same way he has in the last two thousand years and more ago?   Did mankind need a god and religious laws to survive?  Or did mankind create gods to explain his existence, and in doing so gave the creator great power which awed man so much that he worshiped this god and obeyed rules as well as obeying whomever had special access to that god?  

Definitely, man seems very susceptible to the thought of religion, which gives religion tremendous power over large groups of people.  But why is it so powerful?  As such, atheists astound me.  Ignoring thousands of years of religion and the power it has had over mankind, they are capable of simply obeying laws because of their altruistic advantage.  When a person thinks of morality, religion comes to mind as the source and power of it.  Yet to an atheist, morality means a code of behavior most conducive to survival, or does it?  If man was capable of evolving without the creation of gods, why did he create them?  If life is just about survival  would not killing, stealing,cheating, etc in many cases be about personal survival and, therefore,, valid?   Does religion exist in the back of everyone's mind?  Does it hold the highest power of morality or does man himself?  If one could have millions of dollars by killing one man and know he could easily get away with it, what would be stopping him?  Is human morality enough, or does an eternal hell need to exist?  

There remains one other answer: man did not create a god but has been simply trying to describe and understand something which exists that he can sense, but not yet understand or explain.