The short book Why we Believe in God(s) by J. Anderson Thomson with Clare Aukofer (2011) marshals the evidence that god is a creation of human beings.
In the book, the authors discuss the work of Robert Sapolsky, a professor of biology and neurology at Stanford University, who has “extracted information showing that religious ideas actually can be shaped by geography and ecology. Historically, rain forest dwellers, with nature’s abundance all around, tended to be polytheists, believing in spirits based on nature and less likely to assume that gods intervene in their lives. Desert dwellers, living in a monotonous, harsh, and unforgiving environment, were more likely to believe in a single, sometimes harsh, misogynistic, interventionist god.” (p. 137)
Just our luck that the unpleasant desert version of god has become dominant.
This work supports the ideas of primatologist Frans de Waal that I discussed earlier.