Some people despair of ever stopping the MX missile. There is reason: three presidents have rassled with the critter, and it has made them all say "Uncle."

There is a way, though. Have Reader's Digest call it a turkey, and the thing is dead as Chelsea.

Reader's Digest, the monthly for people who hate to read, has a circulation of 17,875,545.

The reader who makes the difference is the president of the United States, for whom it is gospel.

You have only to study the transcript of Ronald Reagan's last news conference to see that the staple commodity of the dentist's waiting room is, to him, a bible, even though he's on the airwaves this week pushing hard for the real Bible.

The magazine prunes, clips, compresses and blands all expression to a brevity and conformity that caused Thornton Wilder, possibly its severest critic, to call it a "magazine for boors, by boors about boors."

At that last news conference, the president restated categorically that the Soviet Union is pulling the strings on the nuclear freeze, which, he had told us earlier, is being manipulated by "those who want the weakening of America."

Asked for evidence, he replied briskly, "Yes, there is plenty of evidence. It's even been published by some of your fraternity."

He could not quite bring himself to name his favorite publication, perhaps because he senses that not all reporters share his faith in its infallibility. A few sentences later, he slipped in a reference to "intelligence matters," and nobody in the admininstration seems able to back it up.

But when he has Reader's Digest, he doesn't need intelligence reports. The hot item in the October issue, "The KGB's Magical War for 'Peace,' " was enough for him. It's a hard-breathing account about how the KGB is pulling the wool over the eyes of millions of innocent Americans who support the freeze.

It would do no good to cite to the president the multiplicity of the dupes -- from the town of Antrim, N.H., to the Santa Cruz, Calif., Community Credit Union. Nor the distinction of many of its advocates: Harvard's George Kistiakowsky, one of the inventors of the H-bomb, and Nobel laureates Hans Bethe, Owen Chamberlain and Herbert C. Brown. Geniuses they may be in their field, but do they read Reader's Digest? Probably not. They have cut themselves off from information by which their president sets great store.

You understand the depths of the president's belief in the Digest when you see how he discounts material from other sources.

At the same news conference, a reporter made so bold as to question the value of certain weapons that have not done well in tests. The Pershing II missile, which after two bad starts was finally fired successfully last week, was cited. So was an antitank weapon that can't quite cut it against Soviet tanks and a missile that can't seem to find its targets.

These failures have been amply recorded by the embarrassed military services that bought them. They have transmitted these reports to newspapers that like to think they have achieved respectability, and even credibility. But not with Ronald Reagan.

"I've read all those same articles also and having access to information close to the source," he said, with scant regard for the quality of military reporting. "I don't believe those things about the weaponry."

Well, he certainly didn't read about them in Reader's Digest. The Digest has better things to do than dump on U.S. weapons systems. It invites contemplation of "a more picturesque speech," of noble dogs, invincible mothers and the intellectual challenge of a department called, "It Pays to Enrich Your Word Power." The November issue introduces the folks, for instance to the word "bland." That scarcely seems necessary.

The Digest, like the president, doesn't like people to be negative about nuclear war. Edward Teller has an upbeat piece in the November number in which he lays bare "Dangerous Myths About Nuclear Arms." He admits that such arms could, if used, have a downside but assures us that "our survival can be considered certain."

So, as we remarked earlier, the good news is that if the Digest would decide that the MX won't do and then publish an article to that effect, President Reagan would certainly read it and might cancel the program. The bad news is that the Digest will never do it.

Nobody knows how much MX -- excuse, please, that's "Peacekeeper" -- will cost or even if it will work. But these are details that will never infiltrate the pages of Reader's Digest, so we're stuck with it.