Its advocates call it an issue whose time has finally come. Its opponents insist it is the most serious threat to public education today. The issue: book censorship in the public schools. It has sparked an emotion-laden controversy that has reared its head again - alarming and dividing educators, librarians, and parents up and down-nation.
Although hardly a new phenomenon, censorship thrusts launched against books and materials used in schools have reached new, and some say ''epidemic,'' proportions. Teachers and librarians in every state are reporting increased numbers of inquiries and protests from parents, ministers, and community groups over printed matter used in the schools. And in more than one community, legal battles are ensuing over attempted censorship. For instance:
* Up in the far reaches of Maine's northeast corner, just this side of the US border in the quiet mill town of Baileyville, the local school committee has removed from the school library a nonfiction book containing what it called ''offensive and abusive'' words. Said the school superintendent, ''Someone has to have the authority to take a particular book off the shelves.'' Students disagreed. One even filed a class-action suit, which will be heard in federal court in December.
* Down in Tampa, Fla., the city council, responding to complaints from a PTA chairwoman, has ordered the city library to remove a collection of sex-education manuals written for children from its juvenile section and place them in the adult section, in a completely different building.
While most city libraries are governed by independent boards, the Tampa library is run by the city, and by law it must obey the directive. Many libraries have been threatened with censorship, but Tampa's is the first to comply. As yet, no countersuit has been filed.
* In Minnesota, a school board banned the controversial film ''The Lottery,'' labeling it a ''subtle way of accomplishing the destruction of the family unit. . . .'' A district court overturned the board's order, calling the ban ''unconstitutional'' and the school board's objections laced with ''religious overtones.''
Courtrooms are not the only places where questions of censorship are being aired. In fact, legal battles may be only the tip of the censorship iceberg. Beyond increased parental objections and inquiries, many educators cite a general ''chilling effect'' in public classrooms today: Teachers wishing to avoid parental controversy simply ''precensor'' their curriculum choices - an occurrence difficult to monitor.
Nevertheless, objections to school texts and library books continue to grow. The American Civil Liberty Union's Coalition Against Censorship, an alliance of 31 national groups, reports being ''absolutely flooded with calls'' regarding censorship attempts. And a recent 40-page study done by the American Library Association (ALA) and the American Association of Publishers (AAP), titled ''Limiting What Students Shall Read,'' reports that challenges to school materials - library books and texts - are growing nationwide. Judith Krug, director of the ALA's Office for Intellectual Freedom, says censorship complaints are ''triple in number this year over last.''
So numerous and vitriolic are objections now that the Supreme Court has decided to jump into the fray by hearing a five-year-old case of book-banning that occurred in a Long Island high school library in 1976. The decision, some say, will be seen as an explication of the First Amendment that will set an undoubted precedent for years to come.
Largely responsible for the latest ballyhooing of what children should and should not be allowed to read is the resurgence of conservative, fundamentalist groups across the country. Charging that public schools are too liberal and nearly devoid of instruction in traditional values, hundreds of local community groups - including Young Parents Alert and Guardians of Education - and national organizations, such as the Pro-Family Forum and the Eagle Forum, point to declining test scores, increased promiscuity, and violence among youths as indications of a falling moral standard. In an effort to reinstate fundamental Judeo-Christian ethics into the classrooms, these groups are encouraging their members to scrutinize the public schools ever more stringently.
While their stated goal of reinstating values education may be laudable, their methods of scouring library shelves, challenging textbooks and curriculums , are sending ripples of alarm throughout the academic community. The net effect is to ''limit'' rather than expand curriculum material - quite opposite to what women and minority groups lobbied for in the 1960s.
Exactly what are parents seeking when they leaf through their children's libraries and textbooks? Traditionally, the subject that has come under most intense attack in public schools has been sex education. Many parents say it undermines the traditional family unit and results in increased sexual activity among juveniles - one of the most frequently cited examples of a declining moral standard. The ALA reports that half its reported censorship complaints are related to sex-education materials.
Also high on the list for possible banning is modern literature containing language considered ''obscene'' or ''vulgar.'' This broad category ranges from ''The Grapes of Wrath'' to dictionaries containing suggestive definitions.
Says Dr. James Squire, chairman of the AAP and president of Ginn & Co, a textbook publisher, ''We're seeing English texts and sex-education books attacked the most often.'' Why? ''Because we're in a period of intensifying morality.''
The drive for increased morality in the classroom has also spread to the library shelves. Parents are still concerned about required-reading lists despite the fact that many teachers will accommodate objections by permitting a child to read an alternate book.
Dennis O'Brien, president of Bucknell University and a philosophy professor, questions what he calls the ''skewed reasoning'' of those parents and ministers launching such attacks. ''How do they square their morality with that morality of this country - maximum personal freedom?'' he asks.
Despite these protests over possible violations of First Amendment rights, fundamentalists appear undeterred. They say their belief in the Judeo-Christian ethic as the moral and legal bedrock of America deserves outright support from the public school system.
Philip Frost, dean of the school of education at CBN University, a Virginia-based Christian university, puts it this way: ''Textbooks must take very clear positions on these moral issues - the Judian-Christian ethic that underpins our whole society. Where textbooks are silent on this point, they are amoral - which is one step away from being immoral.''
The Pro-Family Forum newsletter contains the following admonitions: ''Examine your child's library and textbooks for immoral, antifamily, and anti-American content. Arrange to view films shown in the classroom. Objectionable material should be taken to the principal. . . . Voice your views to the state schoool board, state legislators, governor, and US congressmen.''
And Phyllis Schlafly, the controversial founder of the conservative Eagle Forum, who is against the Equal Rights Amendment, encourages her followers in a recent newsletter to speak out against objectionable classroom materials. She charges that schools exist today ''to change the students' values and attitudes rather than for the traditional purpose to impart knowledge.''
All this shadowboxing with values moves into the realm of clear-cut debate in a subsequent Schlafly article called ''What is Humanism?''
Writes Mrs. Schlafly: ''Secular Humanism has become the Established Religion of the US public school system.'' It alone, she says, is responsible for the declining test scores and lack of discipline; it alone has caused ''the public schools to eliminate prayer, moral training and the teaching of basics.''
To many conservative parents, the catch phrase ''secular humanism'' means that a belief in man and his shiftable ethics has replaced a conscious acknowledgment of God and absolute laws as the center of thought.
Many of the origins of that concept can be traced to an article commissioned by the conservative Heritage Foundation back in 1975 entitled ''Secular Humanism and the Schools.'' The author, Onalee McGraw, an educational consultant, traced a line of reasoning that culminated in the judgment that the lack of belief in God is the reason for lower test scores and rampant decline of quality in public education. The solution? Eliminate humanism from the schools and all problems will be solved.
Also in 1975, John B. Conlan Jr. (R), then a US representative from Arizona, introduced legislation into Congress to eliminate federal funding for all humanist courses. While his bill passed the House, it did not survive the Senate , Representative Conlan did succeed in ending funding for an earlier humanist course entitled ''Man: A Course of Study.''
Since then, rhetoric against secular humanism has increased. Although the focus has largely been at a grass-roots level, the numbers are significant. For example, an estimated 300 conservative community groups exist in the state of Minnesota alone, observers say.
Among those groups elsewhere gaining strength regionally is an independent textbook review house, Educational Research Analysts - better known as Mel and Norma Gabler of Longview, Texas. No telephone listing exists for this enterprise , only for Mel Gabler. And in fact, Mel and Norma still operate out of the same ranch-style house they started in 20 years ago. Today their company, or what they call a ''faith missionary,'' has grown to a worldwide organization with a mailing list of over 12,000.
Educators and publishers consider the Gablers a force to be reckoned with. Armed with a staff of seven, the Gablers read 50 to 60 books a year, marking objectionable passages and submitting their reviews to the state textbook selection committee. School texts in Texas, as in 22 other states, are selected by a single statewide authority. Neither of the Gablers has a college degree or has ever taught school. Last year, out of the 15 texts to which they objected, 11 were rejected by the state.
Additional fuel for the book banning fire comes from the fact that Texas purchases the greatest number of textbooks of any state in the union. Ed Jenkinson, an education professor at Indiana University, says: ''As Texas goes, so goes the nation. Publishers freely admit their texts must be adopted (statewide) in order to make money.'' And the Gablers say that the books adopted in Texas are also used across the country.
Just what the Gablers seek out for criticism spans a broad, but almost predictable, line of reasoning. Not only are sex education materials and English books screened carefully, but history and social studies texts are also studied for possible antipatriotic, anticapitalism positions.
For example, in a telephone interview, Mr. Gabler discussed a history text implying ''that George Washington had a bad temper.'' He and his wife felt that was unpatriotic. He added: ''We couldn't find any corroborating evidence in any encyclopedias to prove that point at all.''
Through all the controversy and rhetoric about book banning and book censorship, it is clear that many parents feel that their own values are being attacked in the schools and through the literature being presented to their children.
Antiparent material is the catch phrase. Terry Todd of St. Paul, Minn., who last year formed a national committee ironically called Stop Textbook Censorship , says: ''If kids aren't taught to respect their parents, who will they respect?''
What constitutes antiparent material? Anything being taught in school that ''is not in accord with the parent's views,'' Mrs. Todd says. ''The traditional values of capitalism, patriotism, family, have been censored out of the textbooks. That material is antiparent.''
Stop Textbook Censorship now has a representative in every state. Unlike the Gablers, who lean on textbook publishers and the statewide selection committee, Terry Todd deals directly with parents and school districts. Is she successful? She prefers to keep that ''quiet.''
On the other side of this burgeoning controversy, many professional educators , librarians, authors, and nonconservative parents are not at all reluctant to raise their voices in protest over what they call a concerted attempt to alter the face of US public education.
For example, on a midmorning talk show in Boston recently, the president of the Massachusetts Teachers Association literally shouted down the objections of Mel and Norma Gabler with the words ''What you are doing is evil, pernicious, and pervasive. And don't you dare preclude any citizen in this country from making his or her own choices.'' That audience applauded.
Others are just as concerned and angry. Mrs. Krug asks: ''Do we really want professional politicians selecting our reading material?'' Erwin Karp, the attorney for the Author's League, says ''previously, book censorship attempts were annoying, but now they are dangerous and frightening.''
And it is the representatives of the public schools that seem to be protesting the loudest. Says Dorothy Massie of the National Education Association (NEA): ''This is the most serious and important thing happening in education today.'' She sees its roots as residing in a ''confusion in people's minds over public education'' - whether that educational process is meant to be ''nontheistic,'' which is guaranteed by the Constitution, or whether it has become ''atheistic'' or secular humanist in nature. Every criticism of a book, she explains, ''stems from this fear of the atheistic.''
But beyond individual censorship cases, the NEA is more concerned with attempts to discredit public education. ''We are fighting like hell to save our public schools,'' Massie emphasizes.
Charles Park, an education professor at the University of Wisconsin, agrees. ''The public schools do need help,'' he says, ''there is no denying it.'' But, he adds, ''now is not the time to strike at the heart of democracy by kicking public education. Our need is to reaffirm the rights of pluralism and the rights of students to think critically and for all of us to understand diversity in our midst.''