If God came from humans, then doesn't that mean the Devil also came from humans? That also means both are inside. Moral relativity is a two sided coin since, if we can define good/God as relative, we will also define evil/Devil as relative. In this world, lying can be justified as not lying or stealing is not stealing. There are no absolutes, in a relative world. If moral came from man, man can change the morals to make it easier for his God or devil inside. For example, President Obama lied about the affordability of ObamaCare to win an election. But to liberals, this lie is not a lie due to relative evil. The ancients kept God and Satan outside, so there is one set of rule for all, thereby avoiding the pitfalls of each person or group generating their value system since there will be conflict, division, waste and inefficiencies.