I have been suspected of being what is called a Fundamentalist. That is because I never regard any narrative as unhistorical simply on the ground that it includes the miraculous. Some people find the miraculous so hard to believe that they cannot imagine any reason for my acceptance of it other than a prior belief that every sentence of the Old Testament has historical or scientific truth. But this I do not hold, any more than St. Jerome did when he said that Moses described Creation “after the manner of a popular poet” (as we should say, mythically) or than Calvin did when he doubted whether the story of Job were history or fiction.7 (RTS) 105.
Twp things to notice. First, as Don points out, the inerrancy Lewis attributes to the "fundamentalist" is a naive, not a theologically nuanced version of the doctrine. Second, it looks as if Calvin (one of the premier champions of biblical authority in the history of the Church) didn't hold this naive doctrine. However, naive versions of the doctrine can easily be found in pews and pulpits all across the evangelical community. Don seems to think Lewis was "caricaturing" the position, but I think there are plenty of people who fit the caricature to a T. It's just that he's not responding to a theologically underdeveloped version of the doctrine.
My own view is that the question "Do you believe in inerrancy" is a little like asking someone "do you believe in evolution?" Depending on how you explain the doctrine, I might answer either question yes or no. I personally dislike the word inerrancy, and prefer to ask "what hermeneutical constraints follow from believing that Scripture is special revelation from God?"
Evangelical groups committed to inerrancy sometimes do purge members whose interpretations of Scripture do not square with inerrancy as they understand it. Such was the case in the purging of Robert Gundry from the Evangelical Theological Society a number of years ago, based on what they took to be "errantist" interpretation of Matthew.