Just a couple of quickies in response to two different posts:
1. It is no surprise if Catholicism exists 200 billion years in the future, as far as Wolfe is concerned. It is the true religion, so it's never going to disappear.
2. The Christianity in Severian's culture is more Eastern Orthodox, but we see little of it. It is much more "behind the scenes."
3. As for the gods being real gods: Well, the real gods to which Wolfe refers would be the angels and fallen angels who superintended the world before the coming of Christ. This is taught in the Bible and in historical Christian theology. Since Paul says that Christians battle against "principalities, powers, thrones, and dominions," Wolfe sees such demonic princes still active, though not as powerful.
At the same time, I think it pretty clear that the gods of Whorl are computerized, except for the Outsider. They are the remnants of men who play at being gods or God.
That does not, however, answer the question about auguries from entrails. An interesting question!
Nutria