Mystics and true believers are difficult to have around.Invariably they are insufferably assured, irritatingly dogmatic, and grimly determined to foist their beliefs on others. They have seen the light; how dare anyone question their right to lead the way toward truth? Lack of humor is a sure sign of the breed.

Alexander Solzhenitsyn, the great Russian writer now living uneasily in exile in America, is the latest to enter the lists of the self-righteous. He speaks with the fervor of an Old Testament prophet - and with the manner of Moses bringing the revealed World to the wayward masses.

His tone is annoying, to say the least, his judgments delivered with olympian arrogance and without any colorations. Yet in this day of bland public pronouncements, singular lack of eloquence and almost total absence of serious national discourse, the dour Solzhenitsyn has done a Service. He provocatively forces us to examine ourselves and our society. You can rail at his views, but you can't really ignore them, or him.

Solzhenitsyn's is simple, but old-fashioned message. The forces of darkness are warring - and, in his view, wimming - against the forces of light. Evil is a palpable reality; it exits all around us; it gains in power. Again and again he invokes that specter:

The forces of evil have their decisive offensive, you can feel their pressure . . . The inequality has been revealed of freedom for good deeds and freedoms for evil deeds . . . It is again a doomed alliance with evil . . . That provided access for evil, of which in our days there is a free and constant flow . . .

Solzhenitsyn offers us a morality play, as stark and simple in its plot as the science fiction thriller, "Stars Wars," where evil and goodness are pitted and to hell with any subtleties or ambiguities of character and action. He draws his lesson without betraying semblance of doubt. Its essence is familiar: rampant materialism leading to decadence and destruction.

His historical analysis of our dire present condition is more complex. As he sees it, the western world has been heading toward collapse for centuries. Our troubles began, indeed, with the Renaissance, that humanizing period in which art and culture flowered so nobly after the Dark Ages. The prevailing western view of the world that took form than "became the basis for government and social science and could be defined as rationalistic humanism or humanistic autonomy: the proclaimed and enforced autonomy of man from any higher force above him."

Man, in that sense, stood at the center of everything that exists. " . . . We turned our backs upon the Spirit and embraced all that is material with excessive and unwarranted zeal. This new way of thinking which had imposed on us its guidance did not admit the existence of intrinsic evil in man nor did it see any higher task than the attainment of happiness on earth."

Freedom that celebrated quality, eventually became irresponsible and destructive. An excess of freedom, and a decline of values, has led us into decadence, crime, pornography, horror. Again, his somber theme:

Such a tilt of freedom in the direction of evil has come about gradually but it was evidently born primarily out of a humanistic and benevolent concept according to which there is no evil inherent in human nature; the world belongs to mankind and all the defects of life are caused by wrong social systems which must be corrected.

He lectures us severely - and tiresomely - for our naivete, for our weakness, for our lack of will, for our decline of courage, for our failure to understand the world struggle, for our betrayal of allies in Vietnam. He chide us for looking toward China as a buffer from Russia: "at a later date China with its billion people would turn around armed with American weapons [and] America itself would fall prey to a genocide similar to the one perpetrated in Cambodia in our days."

In an apocalyptic visions, he sees a new war occurring which "may well bury western civilization forever." You get the feeling Solzhenitsyn welcomes that prospects. He conveys the ancient sense of the martyr who relishes nothing more than to suffer and die for the Lord. Like Tolstoy, whom he resembles more and more in looks as well as thought, Solzhenitsyn bemoans the retreat from "the moral heritage of Christian centuries with their great reserves of mercy and sacrifice."

Some of the rest of us might blink at that reading of history, recalling all the wars, barbarisms and enslavements commitment in the name of true religion. Spare us such crusades. But Solzhenitsyn plunges forward. He takes us to task for depriving ourselves of "our most precious possession: our spiritual life."

All this is both stimulating and infuriating, it abstract and polemical. But Solzhenitsyn has something else to say that strikes closer to home in this corner. He was speaking of the press, and he delivered a barbed and specific indictment. And also one that holds an uncomfortable amount of truth.

Solzhenitsyn begins his analysis of the press by first raising a question and then by stating a standard and a concern. "What sort of responsibility does a journalist have to his readers, or to history?" he asks. Then: "The press can both stimulate public opinion and miseducate it."

His view of press is of an immature profession that misleads, confuses and shamelessly intrudes on personal privacy while operating under the slogan, "Everyone is entitled to know everything." He goes on:

But this is a false slogan, characteristic of a false era: people also have the right not to know, and it is a much more valuable one. The right not to have their divine souls stuffed with gossip, nonsense, vain talk . . . Hastiness and superficiality are the psychic disease of the 20th century and more than anywhere else this disease is reflected in the press. In-depth analysis of a problem is anathema to the press. It stops at sensational solutions.

Like so much else in his sweeping catalogue of gloomy criticism, this particular assault is surely overdrawn and overstated. Solzhenitsyn appears to have almost no understanding of the role of a free press in a free society. But as we have seen, to him freedom is not the question: "Merely freedom does not in the least solve all the problems of human life and it even adds a number of new ones."

You simply can't brush aside all his criticisms, however. At about the time he was speaking, the accuracy of some of his points was being sadly demonstrated.

If you had the misfortune to watch the premiere of a new TV network news program last week, you probably squirmed in embarrassment. The program, ABC's "20/20," was intented to break new journalistic ground, to be both serious and compelling, and to bid for a national audience. Instead, in what was probably the single worst TV news show, the nation was offered a monument to cheapness, sensationalism, and appalling taste.

It was proof that, however Cassandra-like his pronouncements, however stern his moralizing, however affected his views by personal suffering, however little his understanding of this society, Alexander Solzhenitsyn can be as provocative about shortcomings in America as in Russia.