The nature of evidence

I was listening to a debate between a theist and an atheist the other day on the YouTube and the subject of certainty came up. The theist did what theists often do and invoked the boogy-man of "doubt" That well worn trope of "you can't be 100% sure that there isn't a God" (heard that line so many times) Of course philosophers like Russell dealt with this argument years ago with his teapot argument but the fundamental problem is that most people don't understand what the attributes of evidence need to be for it to be considered to have any purchase on this question. Simply saying that "flowers" or "puppies" are evidence for God is insufficient, flowers and puppies are evidence for evolution and natural selection and the natural world, that's as much as we can say about them; anything else is a catastrophic misunderstanding about the nature of evidence or simply the usual leap of blind-faith. We can't be 100% sure about anything because Human Beings are not omniscient, but we can know things beyond a reasonable doubt. So, the best defense against this line of argument is to turn it around 180 degrees and ask the theist what their percentage belief that their particular God existing is, if they say 100% (which they usually do) you've got them banged to rights.