It might not seem so challenging on one level: I might believe that the sledge hammer doesn't exist, and yet still have my hand broken by it. Belief or not, reality strikes down. It is also my understanding - one step up from belief - that there are layers of reality, which theologians often refer to as onion-like. We may not believe in higher powers - say, in karmic turnaround - yet that disbelief does not matter: the laws, even if they are laws that we do not understand, still apply. For instance, the Plains Indians believed that the Ghost Dance would make them impervious to the Blue Coat's bullets, but it did not - they dropped like flies. In the past, people did not know of microbes and probably would not have believed in them if told - yet millions died from them - and so on. And so we have beliefs, and we have laws - laws that may be operating on us without our knowing, but they are laws none-the-less, and our hands, so to speak, are crushed under certain circumstances whether we believe in them or not.
But then we have the countering power of belief - of a religious person's belief that God or the gods will change things for them if prayed too, or a shaman's belief that his working with the spirits can alter reality, or the neo-quantum physicist's belief that consciousness IS the universe, and that intent in consciousness can also have its effects. Of these cases, the physicist is referring to laws he has inferred from quantum mechanics - in this, his position falls in with one who is working with real, physical or physical-psychic laws that, as of now, are only poorly understood. There is no magic here, but simply a lack of general understanding. In this case, intent can change reality, but only according to these poorly understood laws. There is real evidence that this is so, but it is countered by the inertia of the general system in which most of us are subject.
The shaman seems to me to have an intermediate position, somewhat more to the faith side of the physicist, but still based on the perception of reality. He does talk to spirits, and he does understand many of the effects the spirit world has on this one. This is from his inside perception, and one may claim that he is basing his technique on belief. But HE does not - he perceives the spirits and sees them at work, to either help or harm. Is this a belief system? If so, then the results he sometimes gets may be put under the category of "belief changing reality." Or is it another dimension, so to speak, of reality, with its own laws that interact with our own laws? Then he is more the technician of the spirit world, like the physicist - not operating on belief, but rather on a different level of natural laws.
And then the toughest part - the religious believer and prayer. That prayer can change reality IS clearly a belief, and one that is encouraged to remain a belief by many religions. Islam and Christianity, for instance, highlight FAITH as a moving factor. Mohamed, then, can move mountains, and Christ - "where two or more are gathered in my name" - can also change the outcome of events. Yet this, too, is different from the man who does not believe in this or does believe in that. Faith is rather a singular belief that a higher power exists that can change reality, not the believer himself. This, really, is a shift back to intent, as understood by the physicist, an intent that strikes at the heart of reality because that is what God is, in symbolic form - the heart of reality. We may anthropomorphise him (or her - its all anthropomorphising), but the reality behind the symbol is the heart of existence. It would seem that, with deeply held belief in this heart, one could transcend the limited mind-picture and actually get to that much greater plain of reality that we represent by God. In that way, the faithful could have access to a reality-changing technology. As one Anglican Catholic put it, Christ (an aspect of God) is in our hearts, the center of our being that is related (through love) directly to God. Being in touch with that center could conceivably give one the power - not through magic, but through the apex of the lawful pyramid - to accomplish anything, or nearly so.
So - does simple belief or disbelief make it so or not so? No: but attainment of the the deeper meaning of things does give one the power to make unexplained (to us) changes in this reality. Belief may do so by uniting personal intent with this greater meaning (law of laws), and so have real effects on the world. Of course, one cannot simply wish for anything and get it - it must be in accord with the greater law. That may have a hampering affect, but if would seem that at some point, where intent and belief were pure, the limitations of one's wishes would be understood. But yes, it does seem to me that belief, in its deepest sense, can lead to great changes, both in consciousness and in the physical realm. FK