Why do you argue I can't prove there isn't a God when you can't prove there is one? Simply citing a book, which hasn't been proven to be historically accurate, correct or true, isn't proof of God, only the words of men who want others to believe there is a God.
So, can either be proven? Is the absence of proof of one side proof of the other side? Or is the absence of proof means what it is, neither side can be proven, only believed? And assuming our believe is proof isn't proof, isn't reality, or anything but our imagination and desire to believe it.
So, God is still relative, if God exists or not. And nothing can prove or disprove it.