The idea of the devine and the supernatural is a mental shortcut, the same as saying, we don't know, or can't know. The prevelence of ignorance doesn't support the idea of God either, since alternative theories about the origins of life are relatively recent.
I think this is true insofar as the supernatural is, by definition, mysterious. I doubt that this is the sole characteristic of our experience of "supernatural" phenomena, though. There are plenty of unknown things that we don't attribute to gods or spirits.
I think a crucial difference is this: whereas the unknown can only be accessed by negating its quality of mysteriousness, most religions provide a means of purportedly interacting with a supernatural realm that preserves and even enforces its mystery. So the merely unknown and the supernatural are experienced differently. The unknown is usually confronted with wonder or curiosity. The supernatural
is unknown, so these attitudes are also present; but even though it cannot be explained, the thing in question is still significant in a very personal way. We might say that there is a sense of sacredness, or as Joseph Campbell wrote, a symbolic, dreamlike expression of universal psychological truths. The method of evoking these images is ritual, and it is distinguished from the intellectual quest to explain a wondrous thing by not actually focusing on the object of wonder. A religious person is not interested in explaining his deity, nor is he interested in ensuring that his deity remains unexplained; a sacred object is, to him, inherently unexplainable, and so any attempt to delve into its specific nature would be futile. The utility of the sacred object, then, is not in its explication but in its ability to reflect and illuminate the human psyche through the power of myth.
The reason why God is a mental shortcut for the unknown is not due to intellectual laziness but an earnest lack of interest in the thing it fails to prove. The explanation's use is not as an explanation in the same sense as science -- indeed, most myths take place in a very distant, otherwise forgotten antiquity, whose factuality would be in the traditional cultures a hopelessly moot discussion -- but in the lessons encapsulated within the mythical system, which is a metaphorical map of the unconscious landscape. The idea is to have an explanation that is believable, since an unbelievable myth lacks credibility and is quickly forgotten. Scientific fact was never around to be taken into account, although certainly our future mythologies will have to do that successfully.
