Thing is you can prove that the Earth revolves around the sun. That God exists is just something people will say to you. They won't prove it because there is no proof that God exists.
So, since there isn't any proof that God exists, he might as well not exist until someone tells you that he does.
Whether god exists or not isn't the point. God is the figure head of plenty of religions. He's the holy figure head to whom Christians, Muslims, Jews, etc. must take after in their every day lives.
This doesn't mean that you can't follow another diety and end up decent, however.
Religion is simply a guideline for mislead human beings who need support and stability.
Human beings that can provide themselves support and stability often find no need for a deity to watch over them, and therefor stray from their faith.
Religion is necessary.
