Harris tries to convey that belief resides in and is a result of the various linguistic properties of the brain. He defines it as the acceptance of a statement based on already known evidence or trust in the origin of the statement. I agree with this, but I also think there is another level of belief beyond this.
For as long as I can remember I have had this unshakeable feeling that there is more to this world than what science has so far described, not that what it says is wrong, but rather it's only looking at one small part of the picture. I don't know where this feeling comes from; it does not seem to have arisen from any experience or perception I have had. It's just there.
I believe that consciousness is an existence in and of itself, not just an effect of the physical machinations of the brain. I believe that the brain serves merely as a conduit for this consciousness into the physical realm and as a feedback system to help it think in terms of physical reality. I believe that within its own realm, consciousness is pure knowledge and will, and it is from this knowledge that the feeling I have described comes from. And so this is, I think, another source of belief.