Whether a deity does exist, ALL the gods worshipped by humans are products of the human mind, imo.
I guess that could depend on what one perceives to be a 'god' - for one thing, people used to worship the Sun didn't they? (which is obviously not a product of the human mind - though sometimes with the weather we get in the UK, one would wonder) - some still do worship the Sun (sun worshippers - sunbathing

)
God/Great Spirit is described as Pure Uncondtional Love, Infinite, Eternal, Wise, that which connects all of us, that which connects every atom ... ah there are probably more words we can use, but then again they are just words and God is much more - no words can truly describe