The relatively-new CAMBRIDGE COMPANION TO SCIENCE FICTION includes an essay which dedicates about a page and a half to Wolfe's solar works. The overview isn't terribly in-depth, but I found it most interesting that the writer sees Silk as going on to become "a fisher of men" among the stars at the end of the Book of the Short Sun.
This changed my view of the ending of the BotSS entirely. I originally thought it was an inexplicable and cruel abandoning of Blue by Silkhorn after saving some of his buddies from it (as in the traditional belief of the Harrowing of Hell). Now, however, I can see that perhaps Wolfe wanted it to be an optimistic finale in which worship of the Outsider will spread all over the universe.
Sure, Blue is abandoned by Silkhorn himself, but there are still those who knew Silk, or read Horn's book, so they know of the Outsider, and monotheism might continue on, especially if (as Wolfe's Catholic faith would have it) the Holy Spirit continues its work eternally.
Does the idea of Silk as galactic bringer of good news make anyone else appreciate the ending of BotSS more?
Christopher Culver