Because the odds against happenstance are such that I don't see how it was possible that this wasn't an intentional act. I've studied it in great detail. I don't see how it can be any other way. But more importantly, I've tested it and know it to be true.Sure. Where do you place God? Why not a natural reason?
It works for gravity, or any of the thousands of testable, verifiable, and predictive laws of nature that science has discovered. Any number of which people have suggested the God explanation and have been proven wrong.
What makes this different?