If there is even the possibility of God – which there is, because we cannot know 100% of the knowledge of the Universe, so an atheist would still have to admit that there is still a tiny percentage that there could be a God. If there is a God – He does not have to stay within the boundaries of the natural world. To say it another way, a supernatural power is supernatural because it is outside the natural world and thus it can affect the natural world in unnatural ways.