Three weeks before a Soviet fighter pilot murdered 269 people aboard an unarmed commercial flight to South Korea, the following was written on the editorial page of The Wall Street Journal by Arnold Beichman, recent co-author of "Andropov: New Challenge to the West" and a journalist who is very well connected indeed.

Digest this: "Sometime this year, certainly before December, when the cruise and Pershing II missiles are due for deployment in Western Europe, the Soviet Union (with or without an ailing Yuri Andropov) will do something that will precipitate a confrontation between the two superpowers. The confrontation will be one for which American public opinion will be ill-prepared."

Well, who is this fellow Beichman? He is one of those writers, variously disparaged as a hawk or hard-liner, whom major media have kept at arm's length, for fear that American public opinion might be poisoned by his excessive "anti-communism." Instead, American public opinion has been kept abreast of world conditions by what? Non-communists? Nice people? Liberals?

Well, let them flatter themselves with whatever denomination they choose, but the fact is that there is a consensus among influence molders in this great republic, and for a very long time it has been loath to describe the Soviet Union as the kind of regime that commits the bloody acts chronicled recently by foreign correspondents and historically by eloquent writers from Alexander Solzhenitsyn back to Malcolm Muggeridge in the 1930s.

Last week the French writer Jean- Francois Revel, a man emergent from the left who has never gone any further to the right than the French center, expressed his dismay after talking with American journalists and professors. Revel said their naivet,e about the Soviets--a combative naivet,e out to silence any who doubt it--reminded him of participants in Paris caf,e conversations, circa 1964, where it was chic to purr about the Soviets' good intentions while scorning American vigilance.

Today, Revel says, "Europe is far more anti-Soviet than the United States." All the illusions about Soviet peacefulness have vanished. Even the French Communists make it clear that they do not want to be like Soviet Communists. Yet over here the media echo with delusory reproofs about how we must not overreact, we must deal with the Soviets, we must understand them.

These were the kinds of bromides that issued last week from such consensus columnists as Anthony Lewis and Flora Lewis. Anthony Lewis' column on the downing of the unarmed South Korean airliner devoted most of its hot air to chiding Ronald Reagan for his "rhetoric" and "Manichean ideology." From such flumdiddle I can only deduce that "Manichean ideology" provides more understanding into those who murdered 269 innocents aboard KAL 007 than the platitudinizing of the consensus columnists.

Apparently Lewis never will understand that it has been men like Ronald Reagan and the above-quoted Beichman who have understood the Soviets and whose understanding of them is most likely to keep us all at peace.

Flora Lewis began her column on the massacre at 30,000 feet by intoning: "The most important question provoked by the shooting down of South Korea's Boeing 747 is the relation between political and military decision-making in Moscow," and she concluded that the West must "try to learn how the Kremlin is reasoning."

Outside our media's consensus there are many who know accurately enough how the Kremlin is reasoning. Contrary to Miss Lewis, the most important question provoked by this despicable act is: has the consensus learned anything, have those who inform public opinion learned to shun the dangerous counsels of the peace movement, a movement that wants to turn all America into an unarmed commercial flight?

From the downing of that South Korean flight back to the fall of South Vietnam, no movement in American history has been so soundly discredited by events. Will the consensus come to recognize it as an anti-defense-pro-appeasement movement rather than a peace movement? The only peace it offers is the peace of the grave or the cellblock.

Will influence molders come to recognize the good sense of men like Beichman? I doubt it. This fall ABC plans to broadcast a frightening two- hour, $7 million drama depicting the effects of nuclear war. Thus it will gaudily repeat the shriek that is the heart and soul of the peace movement. ABC will join the anti-defense-pro-appeasement movement in spreading fear rather than the understanding that should be derived from the merciless fate of that South Korean airliner.