No. When I say everything we observe/experience could be demons tricking us, I'm saying that literally, supernatural demons could be tricking us. What I'm saying is that there is no way for us to be certain about anything whatsoever if we allow for the influence of supernatural things/entities in our experience. Thus, for the sake of method, it makes sense for us to assume that they don't exist (or at least, that they have no effect on the world we observe and experience). If we don't make that assumption, then we literally have no way of distinguishing between the validity of any claims. To claim that supernatural demons cause lightning (and only make it appear to be caused by natural forces) would be no less valid than to claim that a supernatural god causes lightning or that an infinite number of other possible supernatural events "really" cause lightning.