The snippet of text in the OP is just really poor writing. It contains numerous errors in grammar which make it difficult to read and understand. The idea he is trying to communicate is fairly simple but his writing style is obfuscating. I took a stab at re-writing just the first paragraph ...
This is a good exercise — Rathbun should really read your version and compare. I'd probably try to go even farther down to ordinary language myself:
The fundamental two-way communication process that all scientology methodology derives its workability from existed before L. Ron Hubbard ever wrote a word on the subject of the mind. All of its components were developed, far beyond the degree of sophistication that scientology ever treated them, while Hubbard was still engaged in black magik rituals in Pasadena. They were perhaps best explained and demonstrated in Rogerian client-centered therapy. It would behoove scientologists to study of it. The best place to start would be On Becoming a Person by Carl R. Rogers (Houghton Mifflin, 1961).
The communication process that makes Scientology work as well as it does is one that existed long before L. Ron Hubbard ever wrote a word about the mind. Other people than Hubbard made it work before Hubbard did, and they made it work better. While Hubbard was still doing black magick rituals, for example, Carl R. Rogers was developing a client-centered approach to therapy that would apply what later became the best parts of Scientology, in a much more sophisticated way than Scientology ever achieved. Anyone who has been impressed by Scientology should read Rogers's book On Becoming a Person (Houghton-Mifflin, 1961).
This is actually slightly longer than what Rathbun wrote, but I've tried to say simple things more simply, and emphasize important things more strongly. I like some of Rathbun's phrases, though. I think he's quite a bad writer now, but he could become quite a good writer by just relaxing a bit, and not trying to stand on so high a soapbox.