I've been thinking a little more about the closing questions I offered in my earlier reflections on Graham Greene's Quiet American--my hunch that somehow the Catholic sacramental imagination has produced better novelists than the Protestant social imaginary.
I should have qualified this, of course, to say that I was thinking primarily of 20th-century novelists--which is why Updike came to mind. It's probably the case that any American novelist in the 20th-century who isn't Catholic is a kind of "Protestant" novelist by default, just because of the ubiquitous protestantism of American culture (somewhat like Hegel said all Western philosophy after Augustine is "Christian" philosophy in some sense). This is obviously the case for Hawthorne and Melville, but might still be the case for 20th-century novelists, at least up to the 60s or so.
Perhaps this line of questioning is untenable, but it does seem instructive somehow. Pen-pal acquaintance Andre Muller (New Zealand) articulated the issue in correspondence: what would it mean for a novel to be "Protestant?"
Well, probably lots of guilt, with no penance! In which case Cormac McCarthy might be the quintessential Protestant novelist (!). More specifically, it seems to me that "Protestant" novels tend toward a kind of didacticism that reflects the cognitivist, "talking-head" way that Protestantism has tended to construe Christian faith. So rather than the obliqueness of Greene, you get something like Marilynne Robinson's Gilead--which is a fabulous book, but not on the order of Waugh or O'Connor (in my humble opinion).
[P.S. While it is unfortunately not available online, those with access to a relatively good library might be interested in my piece on Franz Wright in the most recent Harvard Divinity Bulletin. It's entitled "Absence as a Window." The same issue includes new poems from Wright.]