As freelance prophesies go this really isn't that bad. It's an interesting alloy of neoplatonism, absolute idealism, and the kind of info-messianism you see in devotees of the singularity (all ideas that I strongly disagree with, but whose appeal I think I understand), mixed with Dick's very personal issues with
sibling survivor guilt. If he had somehow written this before 1900 I think James would have quoted from it in the Varieties -- it's just the kind of extreme and idiosyncratic testimony he loves to work on.
At the same time, it's hard to imagine anybody actually converting to Dick's religion. Partly that's because of specific weirdnesses in it, but, even more importantly I think, it's because Dick doesn't make a strong effort to place himself within an existing religious tradition. (He talks about Jesus, but only in a superficial way.) This is a point that I think James makes a serious mistake in overlooking: the really successful prophets in world history -- Jesus, Mohammed, Joseph Smith -- didn't start from scratch, but turned an existing tradition inside out. With his laserlike focus on the purely individual experience, James can't offer a good account of why that is, or whether it's a good thing.