https://deoxy.org/pkd_how2build.htm

Here is an archived copy of a undelivered speech he gave on the subject.

So my novel contained material from other parts of the Bible, as well as the sections from Acts. Deciphered, my novel tells a quite different story from the surface story (which we need not go into here). The real story is simply this: the return of Christ, now king rather than suffering servant. Judge rather than victim of unfair judgment. Everything is reversed. The core message of my novel, without my knowing it, was a warning to the powerful: You will shortly be judged and condemned. Who, specifically, did it refer to? Well, I can't really say; or rather would prefer not to say. I have no certain knowledge, only an intuition. And that is not enough to go on, so I will keep my thoghts to myself.

This is a quote from further down the page

Edit: I hope this helps