To me "Does God exist?" is a question that should be formulated in another way since no one can prove whether He exists or not. I prefer the question "Do you believe in God and why?"
My answer to that question is clearly no. I guess people who use to read my posts around here did not doubt a single second about this
. Though the argumentation is a bit hard to handle with... Let me tell you that I am studying sciences and about to make research my job. That does not make me a materialist but I just love to rationnalize things... and God is not rationnal!
Though as soon as God deeply helps people (and societies or countries) who believe in Him, I consider He is essential and cannot be replaced by anyone or anything. He is also fundamental in human history and took (and still takes) a great place in humanity developpement and behaviors.
So my conclusion would be that God exists for people who believe in Him and because He has been so important for humanity at all times.