Consider this possible news story: American health has deteriorated so drastically in the past two decades that "our very future as a nation and a people" is threatened, according to a study released by the White House. President Reagan said our health-care system was in the "grip of a crisis," and one solution he proposed was to abolish the National Institutes of Health.

Nutty story, right? Of course. But that's about the gist of the White House response to the devastating report on the condition of American education released Tuesday by the National Commission on Educational Excellence. The commission, appointed by Education Secretary Terrel H. Bell, declared: "If an unfriendly foreign power had attempted to impose upon America the mediocre education performance that exists today, we might well have viewed it as an act of war."

But President Reagan's response to what the commission called an "act of unthinking, unilateral educational disarmament" was to ignore the cost of educational recovery and to offer a non sequitur pledge that his administration would "continue to work . . . for passage of tuition tax credits, vouchers, educational savings accounts, voluntary school prayer and abolishing the Department of Education."

The commission's 18-month study produced an alarming catalogue of shortcomings in virtually every phase of basic elements of secondary education. Nearly 40 percent of the nation's 17-year-olds cannot draw inferences from written material, only a fifth can write an essay, and only a third can solve a mathematical problem involving several steps.

Scholastic Aptitude Tests declined without a break from 1963 to 1980, by 50 points in English and 40 points in math. Colleges, businesses and the military are complaining that they are burdened with remedial training in reading, writing, computation and spelling. Teachers are coming from the lower academic ranks.

Given the publicity in recent years about the decline in American education, the commission's report should come as no surprise. Much of what is in it has been said before. Its great value is that it has pulled together all the different symptoms that we have been reading about and sounded an alarm, the likes of which we haven't heard since the Russians beat us into outer space.

There currently are 45.5 million students enrolled in kindergarten through 12th grade, and the commission is telling us in no uncertain terms that millions of them are at risk of coming out of high school incapable of functioning in colleges, the military or the work force. Only 5.1 million of these students are in private schools. Yet President Reagan's answers to the problems outlined by the commission were to limit federal "intrusion" into education and to suggest a series of financial steps that benefit only the private schools and which many contend would harm public schools.

To its credit, the commission avoided politically charged issues such as tuition tax credits, and made a series of no-nonsense recommendations on how to produce better educated young people: longer school days, longer school terms, tougher requirements in social studies, sciences, mathematics and languages for graduation, national standards of achievement. Pointing out that fewer than half of the newly employed math, science and English teachers are qualified to teach those subjects, the commission also recommended higher pay and better training of teachers and some form of reward for teachers who do good jobs.

The task being outlined by the commission is enormous: It will require a great change on the part of teachers, administrators, students and parents, as well as a commitment of manpower and money to a national purpose that has been badly ignored. Given the condition of most state budgets, that means it will cost federal money.

Americans have long recognized that investments in education are investments in the nation's future. This is not the time for politics or for lambasting the Department of Education and ignoring the very useful function it could serve as a clearinghouse in a national effort toward educational recovery.

President Reagan has an opportunity to exercise his considerable leadership skills to chart a course for that recovery. It is a historic opportunity to unite the nation behind a great purpose. But to do that, he will have to acknowledge that it is not enough to pray for excellence in education. We have to pay for it, too.