Don't let the same thing happen, was his point, to the word "Christian."
The same could be said of "evangelical."
Gene Edward Veith does this a little when he prescribes the meaning of "evangelical."
"I think that the term, to be meaningful, must retain its core meaning of holding to the centrality of the Gospel. And some conservative Protestants do NOT make the Gospel central, not really, and so shouldn’t use the name 'evangelical.' ... If you do not believe in the Atonement (as many 'evangelical' theologians don’t anymore), you are NOT an evangelical."Prescriptions of terms like this - or "gentleman" or "Christian" -- do a number of things. Veith's move divides "evangelicals" from evangelicals, for one thing. The prescription cuts through communities, ruling in and ruling out. That can be useful for motivating people to be more of whatever you want them to be. It can also militate against drifting, or softening and can mark as "out" many who might have otherwise would have been thought of as in. It can encourage the vigilance of the faithful, and be employed in defense of doctrine's such as atonement.
What prescriptions like Veith's can't do is describe. The usefulness of the word is diminished when it doesn't describe. If it only designates a position that can be held, and not actually a group of people, not actually something in the world, there are certain formerly sensible sentences that don't make sense anymore. E.g.: Those evangelicals have totally abandoned the traditional evangelical understand of the atonement.
What such prescriptions can't do is help one understand evangelicals as they actually are, in the world, as communities.
Theologically, Veith's move makes sense, but it leads to a lot of misunderstanding and confusions on the ground, with people thinking there are evangelicals who are somehow not "real."
What an evangelical is needs to be distinguished from what one should be if we want to understand evangelicals, rather than preach to them.
Al Mohler -- I'm more surprised by this than anyone, but what's due is due -- does a better job at saying what "evangelical" is. He does stray into the prescriptive a bit at the start, giving a definition and then saying, "In any event, this is what we should hope to recognize as authentically evangelical." But, for the most part, Mohler does a descent job recounting briefly the history of the term "evangelical."
Two things I'd add:
1) Mohler downplays the extent to which the term emerged in its present form as an alternative to "fundamentalism." When evangelicals started using the term to describe themselves in the 20th century, the distinction being made was mostly, mainly, from the unyielding and aggressive militancy of those whom they agreed with, doctrinally, but whose style, rhetoric, and general modus operandi was thought to be deeply unhelpful.
Mohler himself substantially continues the tradition of the fundamentalists, there, but wants to claim the name "evangelical," too, so doesn't point out how the evangelicals were the moderates, conciliatory and open to cooperation and conversation with those they saw as too liberal. He's eliding this part of this history, and there's some co-opting going on.
Since fundamentalists abandoned their central tenant of separatism, making common cause with Catholics, for example, it's gotten a lot harder to distinguish between fundamentalists and evangelicals. In some ways, there aren't fundamentalists really anymore. It'd be surprising, for example, to hear a preacher oppose voting for a conservative Catholic like Rick Santorum in the same way he might oppose supporting a Mormon like Mitt Romney, but anti-Catholicism used to be de rigueur for fundamentalists. Now we have things like the "Manhattan Declaration."
On the other hand, evangelicals have become more fundamentalists, in the sense that they tend to be more willing and more eager to define Christians who disagree with them as traitors and not Christians at all. The rhetoric of the fundamentalists in the Fundamentalist-Modernist controversies -- e.g., J. Gresham Machen writing that "modern liberalism not only is a different religion from Christianity but belongs in a totally different class of religions" and "the liberal attempt at reconciling Christianity with modern science has really relinquished everything distinctive of Christianity" -- has become fairly standard for Evangelicals. Mohler being a prime example.
Evangelicals who claimed that name in the mid-20th century, leading to it's wide-spread use today, were doing so to try to interrupt the Fundamentalist-Modernist fight, saying there was a third option. Certain accounts of the term and uses of the term act to actually reestablish the dichotomy of either-or.
2) Academically, there's a pretty standard definition of "evangelical," which isn't perfect, but works well enough. It's better if the definition is supplemented with some history and an account, too, of the specific people being looked at and their self-understandings and self-descriptions, but the definition used by scholars is a good descriptive definition.
Neither Mohler nor Veith mention the standardly-accepted "quadrilateral" developed by David Bebbington, though I don't know why. Bebbington says, historically, as they have actually lived and acted in the world, evangelicals can be identified by four things:
- Biblicism - which is the hermaneutic of "plain reading," the text as ultimate authority, infallible and the word of God in the world, and also the idea of the books' incredible power, which leads to Bibles in hotel rooms, read out on the radio, etc.
- Crucicentrism - which normally works out as emphatic support for the doctrine of penal substitution, "there's power in the blood" etc., but is also to distinguish from those who emphasize the priority of the incarnation.
- Conversionism - which Barry Hankins calls "the doctrine of sola fides with a revivalist twist."
- Activism - which is a big part of the history, from the causes of prohibition and woman's sufferage of a previous era to the "family values" activism of today, but which just basically means that the first 3/4 of the quadrilateral are supposed to be worked out somehow in life.
It will, however, be more helpful if you want to try and understand who Evangelicals are, and have been, and how they behave and why they behave as they do.