Here’s a great quote from Adam Nicolson’s God’s Secretaries: The Making of the King James Bible:
“A puritan is such a one,” the London lawyer John Manningham wrote in 1602, “as loves God with all his soul, but hates his neighbour with all his heart.” Anyone who took a stricter line on the demands of scripture than the person speaking could be labelled a Puritan.
Nicolson points out that the definition and shape of Puritanism was a point of disagreement in Jacobean England.
Reading this, of course, I immediately thought of American Protestant Christian fundamentalism. Statistically speaking, I think “fundamentalist” is a slur used by detractors more often than it is a badge of honor worn by the faithful. “Fundamentalist” usually means “a nasty, brutish, short person to the right of me.”
I also thought of evangelicalism. The most famous and enduring definition of evangelicalism is, without question, David Bebbington’s quadrilateral: biblicism, conversionism, activism, and crucicentrism. But this definition is not universally accepted. A lot of discussion goes on over whether evangelicalism ought to be viewed as a center-bounded set or a boundary-bounded set.
One of the reasons the question of definition is so difficult is that some want to answer descriptively (evangelicalism is a sociological group sharing such and such characteristics) and some want to answer prescriptively (evangelicalism is a doctrinal position that holds such and such propositions to be true). The fight gets confused over what people who calls themselves evangelicals say they are—a wide range of things—and what doctrinal watchdogs, mainly on the right, say they ought to be.
If you don’t understand the difference between a prescriptive and a descriptive definition, confusion is inevitable. That linguistic distinction helps bring some clarity: there are two questions at issue, 1) what people who call themselves “evangelicals” or “fundamentalists” actually say they are and 2) what those two groups ought to be.