It doesn't work to say God is the product of man. You would be suggesting that belief in a "higher power" is psychologically beneficial to us as a species and a product of evolution. Even if you could put together a sociological study to support such a theory it would be ridden with logical paradoxes. C.S. Lewis illuminates many of them in his work
The Abolition of Man. Even then it becomes a moot point really. If God exists and he revealed himself to us visa vi his Word then its beneficial to know and draw close to our creator. If not then you should still believe in God because obviously it was a beneficial enough of a human trait that it has been instill via evolution for our benefit for the past thousands of years

The only time God becomes a negative influence in the lives of people is when we reduces him to religion, i.e. a set of rules i have to follow to be "good", not a relationship i experience because my creator loves me.