I have a couple of problems with the OP, the first of which is what can we actually call supernatural? To say that unexplained = supernatural doesn't really cut it. How eels reproduce is largely unexplained (unless I'm seriously behind here, it's not something I read up on a great deal
) but you could hardly consider it supernatural.
Likewise saying the supernatural = something that doesn't fit into a materialist point of view doesn't really work. It relies on a lack of physical knowledge about a subject to apply and essentially this view of the supernatural eventually becomes the same as the previous one; supernatural = unexplained.
To me "supernatural" is a largely arbitrary word which describes things that follow a certain theme. Ghosts, werewolves, magic and so on are typically classed as supernatural. The thing is, you can have a fair crack at explaining them in a way that fits in neatly with a materialist view. All sorts of electrical malfunctions and weather conditions can create a haunted house. Lycanthropy may be exceedingly rare but it's not unheard of, the same goes for feral children. Finally blessings and curses can largely be explained as placebo/nocebo (granted there is some ambiguity in the two terms when applied to anthropology rather than medicine).
My other problem is the idea of non-believers simply discarding the supernatural. Some people certainly do, there are plenty of wikipedia scientists around who will believe something only if it
sounds scientific. However it's not fair to lump people together like that. I've spoken with plenty of people who don't believe ghosts et al exist, but who will quite happily give their views on how they might
appear to exist. I've already given some examples of mundane explanations for apparently supernatural phenomena and there are lots of people who feel that these explanations are more than adequate.
Now I myself don't quite agree with this view as to me it can quite easily become a comfort blanket. We know very little about our universe and easy explanations often strike me as presumptuous.
However, that's not to say they don't have merit. If a haunted house can be explained as being the result of faulty wiring I'm quite happy to concede that there never were ghosts there to begin with. Sometimes the simplest answer really is the best one.
Now for my final quibble, any discussion of the supernatural will eventually become a game of semantics and contrasting worldviews. Placebo to one person is magic to another and so on. I kind of get what you're driving at with your OP, but I feel that you need to really try and get to grips with how different perspectives can clash. RF may have its fair share of Wikipedia Scientists and they are often a vocal group, but that doesn't mean they're the only people in the "non-believer" camp.