A PRAYER FOR OWEN MEANY By John Irving. 543 pp. New York: William Morrow & Company. $19.95.

Our Presidents continue to pour the soothing syrup. But some of our most talented novelists see the political condition of American society as a disaster, the temper of many Americans as correspondingly dangerous. In ''A Prayer for Owen Meany'' John Irving makes it all too plain, and with positive rage, that in his eyes American society has been a moral disaster since the 1960's. He instances the America that snickered at President Kennedy's amours in the White House, the Vietnam War that sacrificed more than 58,000 of our young men, the moralizing and piety of national leaders who refuse to hinder the traffic in weapons of every kind, to say nothing of a widespread appetite for drugs and the ''junk food'' of television, which ''gives good disaster.''

Desperate conditions invite desperate remedies. In ''A Prayer for Owen Meany'' this takes the form, originating in a town very like Exeter, N.H., and in a school that pleasantly caricatures the old regime at Phillips Exeter Academy, of sainthood - and perhaps something more than that? The center of the book is a little squirt who reminds me, at least, of Truman Capote (outwardly) and has a peculiarly faint voice to match. To be understood, he talks in what Mr. Irving represents as oversized capital letters. Part of his cuteness is that he even writes his diary in LETTERS BIGGER THAN THESE without ever deviating.

In Puritan Massachusetts there was a staunchly independent Congregationalist minister, John Wheelwright, who supported his famously independent sister-in-law, Anne Hutchinson; because of his own mental freedom he was also banished from godly Boston by the ayatollahs of the day. He founded a congregation in Exeter, where John Irving was born and went to school at Phillips Exeter. I have always been fascinated by the destiny of the Puritans' descendants. I remember with relish the poet John Wheelwright, who was a follower of that overconfident, unfortunate prophet Leon Trotsky and was rumored to don a tuxedo to read his poetry in the Boston streets.

The narrator of ''A Prayer for Owen Meany'' is another John Wheelwright, also a descendant, but a good deal of a conscious and unapologetic wimp. Although he had half of his right forefinger amputated by Owen Meany so he could stay out of the Vietnam War (more about this later), out of disgust with his native land he emigrated to Toronto, where he teaches English literature in an Anglican academy for young ladies. (He has abandoned his ancestral Congregationalism for the Episcopal Church in America, the Anglican Church in Canada, and his constant companion is the Book of Common Prayer.) The book is as discursive as an undergraduate bull session, and the plot, simplicity itself, raises as many questions as stories of miracles usually do. Owen Meany, the little saint (the scene in which he is left hanging on a coat hook also suggests a ''Christ figure''), is unrecognized by all in the school town except his straight man and adoring disciple, the narrator John Wheelwright. Strange occurrences: Owen ''accidentally'' kills the narrator's mother (more about this later), and not only feels no guilt but manages to persuade the son that it was all foreseen (which means desired) by God. Since the narrator is illegitimate, her death seems necessary to our comprehending the inner perfection of a woman outwardly ''immoral.'' Strange occurrences: Owen foresees the exact day of his death as a martyr. His ''inside'' knowledge convinces him that he is God's messenger. Because he is so odd-looking and odd-sounding, he acts out the necessary paradox on earth suitable to men altogether holy within, though he can drink beer to excess and sleeps with the one girl in town unconventional enough to appreciate his stern disapproval of contemporary goings-on. Owen foresees everything in his life; in the startling climax he achieves martyrdom in the most exemplary way. But will this be really understood and appreciated by this damned generation?

What makes John Wheelwright the narrator important to the book is that he reports Owen's - and clearly John Irving's - raging displeasure with such American phenomena (and these are only a few) as Kennedy's inception of the Vietnam disaster; Johnson's helpless expansion of it; teen-age idiots in camouflage uniforms who are stupid with rock music and marijuana; television sought as a solace and acting as a drug. There is much, much else on the burning subject of America's moral failures, political chicanery high and low, the cant common to officialdom, the failure of the churches.

John Wheelwright is a lifelong virgin because of his spiritual fascination with the tiny saint-hero, Owen Meany - who, interestingly, is not a virgin. And then there is the mystery of good in an evil world that lies at the heart of the novel: Owen Meany at the age of 11 killed Wheelwright's mother, a ''perfect'' woman he adored, when, at bat in a school baseball game, he managed for the first time in his life to get a ''decent hit'' - a foul ball. This foul smashed into the left temple of the dear woman as she strayed onto the field and turned around to wave to someone in the stands.

I find it preposterous that John Wheelwright not only bears no grudge against the (accidental) killer of his mother but learns to reverence him because Owen is so sure that the death was foreseen, in God's hands. Does she have to die in order to make the point that there is a mystery to this our life that we have to accept if we are to believe in a providence? This may be true in general, but here in New Hampshire the point is so forced that it is repellent. And does Owen Meany ever believe, because his parents (in some confusion) told him, that his was a virgin birth? Is it really a proof of spiritual powers that Owen Meany, while acting in a school production of ''A Christmas Carol,'' should see on the stage tombstone the exact date not only of Scrooge's death but of his own? Does the corpse of a pet armadillo have to be deprived of its claws, as the Indian founder of the town is pictured without arms, in order to make the point that the world is besotted with weapons? This seems to be an argument not for peace but for impotence, as is the grisly episode, bearing still another symbol, in which John Wheelwright has half his right forefinger amputated by Owen Meany (with a saw used for cutting granite) in order to get him out of the Vietnam War. He gets to Canada anyway, so why not with a whole forefinger?

I do not know the answers. What I do know is that John Irving favors ''characters,'' not character, and has an obvious taste for featuring oddballs, zanies, freaks, ''originals.'' In this novel they remind me not of the lives of saints but of George Price's wonderfully distorted cartoon families, their members forever eyeing one another suspiciously in their own homes. John Wheelwright and Owen Meany love each other almost as much as John Irving loves them, the ''good'' characters, to the death. Clearly, Mr. Irving has come to such a point in his revulsion from our disorder that he has decided (this is hardly novel in ''religious'' fiction) that the true saints and even ''Christ figures'' are the oddballs, and that only such can do anything about this gashed, violent, yet morally torpid society. And unlike us conformist sheep, who are all too comprehensible and classifiable, they test and provoke us not just beyond endurance but beyond our comprehension. Traditional enough! But it is what we do comprehend here that makes for a problem.

The essence of ''A Prayer for Owen Meany'' - he dies on the date foretold to him, but in a way totally unexpected (I can say that he dies because of the Vietnam War and because of what it did to the American temper) - is that though we cannot understand Owen Meany's life and death in ''ordinary,'' rational terms, we are expected to understand both as a miracle.

My problem is that John Irving's obvious excitement with all this does not translate convincingly as fiction. It is just pushed at us enthusiastically. There is something much too cute about Owen's conviction that since he can foretell so much he must be God's instrument. It never seems to occur to John Wheelwright, the devoted Anglican in Canada, that his prophet Owen is caricaturing Calvinist predestination in the role of fortuneteller. To believe that everything is in God's hands hardly entitles anyone to believe that everything is determined in advance and that he knows exactly what will happen. This is astrology and denies the principle of free will.

John Irving, whose six previous novels include ''The Cider House Rules'' and ''The World According to Garp,'' is an abundantly and even joyfully talented storyteller. He is a natural crowd pleaser, not least because his values are simplistic, brilliantly cinematic in the way he positions good against evil. He can be very funny, as in the delicious scene of a student rebellion against a tyrannical headmaster. It is already so perfect for the movies that I laughed as one does only in the movies. But Mr. Irving is terribly in earnest most of the time, politically and sacramentally, with the same easy sense of virtue. The book is as cunningly contrived as the most skillful mystery story - that is the best of it. But there is absolutely no irony.

Our land is in such a state that a miracle man is a necessary symbol of a new kind of thinking among us. Mr. Irving shows considerable skill as scene after scene mounts to its moving climax. But the thinking behind it all seems juvenile, preppy, is much too pleased with itself. There is something appropriate in the fact that so much of the book takes place in and around a New England academy. The heavily emphasized ''religious'' symbols at the center of the book - the contrast to American aggressiveness offered by the clawlessness of the armadillo, the armlessness of the Indian founder of the town, even John Wheelwright's imbecile joy at being mutilated as still another symbol of his sacrifice of sex to right thinking - all this reminds this long-tried teacher of all the ''Christ symbols'' his students find in everything and anything they have to read.

I am told everywhere that we are undergoing a religious revival. Maybe so. What I, at least, seem to see is a lot of hopeful language and a frightening, intolerant fundamentalism when it is not, as it is in official Washington, the most chilling public relations. I shuddered when Mike Wallace, interviewing President Reagan just before he left the White House, addressed him as ''a spiritual person.'' Franz Kafka, who respected religion but like many of us was not altogether certain about what goes on in heaven, said to a Christian admirer in Prague: ''He who has faith cannot talk about it. He who has no faith should not talk about it.'' There is lots and lots of talk about ''religion''in this book. John Irving is a talented man and politically more outspoken than most of us, but the talk is on a level with the examples Mr. Irving gives of American superficiality, shoddiness, frivolity.

Flannery O'Connor, one of the few American novelists of my time I am sure will be read well into the next century, was an absolutely, tyrannically believing Roman Catholic who made life difficult even for her parish priest (he told me so) because she disapproved of his literary tastes. In a letter to a friend in 1955, she described a conversation with Mary McCarthy in which Miss McCarthy, who had left the church at 15, said she had come to think of the Holy Ghost ''as a symbol and implied that it was a pretty good one.'' O'Connor: ''I then said, in a very shaky voice, 'Well, if it's a symbol, to hell with it.' That was all the defense I was capable of but I realize now that this is all I will ever be able to say about it, outside a story, except that it is the center of existence for me; all the rest is expendable.''

I have long had the feeling that the passion of that statement has something to do with the steely precision with which Flannery O'Connor indicated her dissatisfaction with human character. Her own character, as she often said, was not so hot. She did not ''love'' her characters. There are so few ''good'' ones! But then, she was not a ''spiritual person.'' Casting Doubt on Atheism

''Jesus has always struck me as a perfect victim and a perfect hero,'' said John Irving, explaining the genesis of his seventh novel, ''A Prayer for Owen Meany.'' The story about a freakishly diminutive self-proclaimed prophet and his effect on the religious belief of his lifelong friend represents ''a natural progression'' for Mr. Irving.

''Like most teen-agers, for 19 years I sat in church and hated every minute,'' said the 42-year-old writer during a telephone interview from his home in Grafton, Vt., ''but that accumulated time takes a toll or leaves you with images that cast a doubt on one's former atheism.''

It was the element of precognition in the Gospels that appealed to his artistic imagination, Mr. Irving said. ''One event that always got me was that Jesus told his disciples that they were going to betray him.'' In the novel, Owen Meany issues a series of prophecies - including one of his death - that find an often ironic fulfillment.

''Owen Meany does seem to possess a kind of moral certainty and acts as one who is in possession of one piece of information that cannot be explained in the natural world,'' Mr. Irving said. After a lifetime of witness, the novel's narrator comes to believe in God.

''What degree of religious belief I can manage owes as much to personal experience as it does to all those years of conscious and subconscious training within church,'' Mr. Irving said. ''When I am moved to see beyond my usual doubt, when I am moved to something that approaches real faith, it seems to me, I am basing those instincts for belief on personal experience as much I am on any formal religious training.'' MICHAEL ANDERSON