I agree with Uwe. Otherwise it would have to read: he took the pledge to renounce alcohol.

Supported. Being on the 8th floor with a fire on the 5th and not being able to get down I pledged never to live in a high rise block of flats. That was almost 10 years ago and I am now living in a typical English two up, two down.

NOAD:
pledge - ... • (the pledge) a solemn undertaking to abstain from alcohol: 'she persuaded Arthur to take the pledge.'

Random House unabridged:
pledge - ... 9. take the pledge - to make a solemn, formal vow to abstain from intoxicating drink.

Webster's 3rd unabridged:
pledge - ... 8 ... b: a promise usu. in writing to refrain from intoxicants or something considered harmful — usu. used with 'the'

OED:
pledge - ... 5. ... b. the (temperance, total abstinence) pledge - a solemn engagement to abstain from intoxicating drink. Phrases: to take, sign, keep the pledge.

I support leaving the entry unchanged. The expression dates back to the temperance movement that began in the 1830s and continued throughout the 19th century and beyond in both America and Britain. (BTW, was there a similar movement in German-speaking countries?)

Ever since, 'take THE pledge' has indeed meant specifically to renounce alcohol. So it would normally be unnecessary, even redundant, to add a clarifying phrase mentioning alcohol. And it would be an error to confuse this phrase with 'take A pledge' or, as Karin wrote, simply 'pledge.' Both those have a much wider range of meaning, which is already covered by LEO's definitions of 'pledge' as a noun and a verb.

As for web hits, many occurrences in other contexts may be deliberate plays on the original expression, suggesting swearing off some other harmful habit with the same quasi-religious fervor as a reformed drinker. But obviously, non-native speakers need to be aware of the original phrase in order to understand fully such takeoffs on the concept.

Given the unreliability of web examples, some instances may also simply be mistakes by people who aren't familiar with the phrase and its history. And of course, in many cases 'the pledge' may often simply refer back to _a_ previously mentioned pledge, as with 'a' and 'the' and any other noun. But none of that is relevant to this fixed phrase and its definition, which are correct as they stand.

I think today, if you say "to take the pledge" people think of sexual abstinence before marriage first. I would support to take the phrase out. You can stop drinking without "taking a pledge". And you can "take the pledge" for lots of other things. Too confusing.

@Tweety: Again, it's possible that you may be confusing 'take A pledge' with 'take THE pledge.' I understand that it can be disconcerting to discover that a phrase has a meaning you weren't aware of, but the fact remains that the phrase exists and the translation given is correct.

BTW, hope you won't mind my mentioning that 'support' takes the gerund: support taking sth. out/leaving sth. in. (-:

Vielleicht könnte man den Begriff als altmodisch kennzeichnen? Wenn es inzwischen eine Bedeutungserweiterung gibt, wäre eventuell ein ergänzender Eintrag sinnvoll (vgl Websters 3rd).

Bei Duden/Oxford sind die obigen Übersetzungen enthalten, die ME passender sind und das verpflichtenden betonen. (Entsagen kan ja auch mal vorüebergehend sein).

Ich weiß nichts von einer Abstinenzler-Bewegung in Deutschland im 19 Jhdt - entweder es gab keine oder ich weiß weniger über Deutsche Geschichte als Amerikanische. Gab es in England ein Temperance Movement?

Ja, es gibt eine Abstinenzler-Bewegung in Deutschland: die Guttempler (gegründet 1889).

@ Paul M: Mir sind die Guttempler als Gemeinschaft bekannt, die Hilfe für Alkeholiker anbieten. Die Abstinenzlerbewegeung ist ME eher durch allgemein moralische Predigten und Versuche der politischen Einflussnahme aufgefallen als durch konkrete Hilfe.

It's definitely a standing expression and should be left in -- whether or not CJ de's alternatives in German are better should be decided

@CJ de: Brockhaus schreibt über die Guttempler: "Der politisch und konfessionell neutrale Orden verpflichtet seine Mitglieder zu völliger Abstinenz."

Na, wenn das keine Abstinenzler sind...

@Paul M.: In der (heutigen) deutschen Sprache ist ein Abstinezler jemand, der keinen Alkohol trinkt.
laut Brittanica 2003 war das temperance movement eine umfassende POLITISCHE Bewegung, die Einfluss auf die Gesatzgebung nahm:
movement dedicated to promoting moderation and, more often, complete abstinence in the use of intoxicating liquor. Although an abstinence pledge had been introduced by churches as early as 1800, the earliest temperance organizations seem to have been those founded at Saratoga, New York, in 1808 and in Massachusetts in 1813. The movement spread rapidly under the influence of the churches; by 1833 there were 6,000 local societies in several U.S. states.

Temperance and abstinence became the objects of education and legislation in many regions. Besides combining moral and political action, the modern temperance movements were characterized by international scope and the organized cooperation of women. The first international temperance organization appears to have been the Order of Good Templars (formed in 1851 at Utica, New York), which gradually spread over the United States, Canada, Great Britain, Scandinavia, several other European countries, Australasia, India, parts of Africa, and South America. In 1909 a world prohibition conference in London resulted in the foundation of an International Prohibition Confederation.

und weiter..

A U.S. organization that became international was the national Woman's Christian Temperance Union, founded in Cleveland, Ohio, in 1874. The WCTU employed educational and social as well as political means in promoting legislation. During the 1880s the organization spread to other lands, and in 1883 the World's Woman's Christian Temperance Union was formed. See also prohibition.

Sofern ich davon ausgehen kann, daß der Order of Good Templars die Guttempler sind, scheinen sie zumindest in dieser Tradition zu stehen. Die Interessante Frage ist jedoch, seit wann sie hierzulande aktiv sind und ob sie jemals soviel Einfluß hatten wie die temperance societies in der USA.

BTW: Wahrig kennt Temperenzler=Angehöriger eines Temperenzvereins und Temperenzverein=Verein zur Verbreitung der Enthaltsamkeit von Alkohol.