The biblical documents have been transmitted well enough to give us a reliable text that is well documented to be from eyewitnesses of the events described. And this is not a singular book, but 66 books over a thousand years from many different authors. Despite that the biblical writings display a remarkable level of unity and consistency with arguably no contradictions. And naturalistic explanations do not explain this pattern. So the best explanation is that the text is divinely inspired. Therefore the christian God exists.