As part of our conversation about revelation, consider as fundamental the approach of someone like Hilarius, bishop of Poitiers in the mid-4th cent.
Cardinal Dulles will eventually get around to defending this view of revelation, but not until the end of the book. If we take it in order, we could seem to flounder for a while. So hold onto this solidity in the meantime. Dulles doesn't abandon it, but it does take him a little while to get back to it, while he thoroughly considers the objections according to each model he'll describe.