It seems that what some people struggle with here (and that's theists and atheists) is what it means to assess something that is a) claimed to be outside of nature, and b) to be the reason that nature exists. This means that all natural phenomena that occurs can be traced back to the source of nature, so there is nothing that exists in nature that can't be evidence for the supernatural. This leaves us with no contrast, like a universe where temperature is the same everywhere yet people think they can make sense of hot and cold.
Also, this problem is compounded by nature holding no constraints over this supernatural thing. Even if it wasn't claimed to be the reason nature exists, you still couldn't fathom where the supernatural had intervened and where it hadn't, as no matter where on the spectrum the natural phenomena is, whether it's at the outlandish or mundane end, the temperature is the same.