Just 10 minutes from Harvard Square, the country's largest liberal playground, stands the headquarters of the John Birch Society, the arch-conservative group which believes a "global conspiracy" today threatens society with worldwide communism.

"If you want to know the truth, that's why we're so controversial," says the Society's public relations director, John F. McManus, in his Belmont office.

But the organization's radical public image also rests heavily on its stands against such institutions as Social Security, public education and nation-wide suffrage. It frequently sparks the interest of the press by claiming that elaborate conspiracies are responsible for the Equal Rights Amendment, the Presidential candidacies of George McGovern and Nelson Rockefeller, and the fluoridation of our public water supply.

Many Americans also associate the Society with the Ku Klux Klan, Nazism, racism, anti-Semitism, and book burning.

Regardless of political stance, however, most observers agree that the Society--which reached its height in the mid-'60s--is now more an interesting relic than a strong political force. McManus likes to say that the organization was partly responsible for the nation's electoral surge to the right in 1980, but most analysts of popular opinion doubt that.

One critical political activist even suggests that the country's conservative shift--if it can still be called that--has actually hurt John Birch. "They represent the extreme right of the past. People identify with the Moral Majority more so than the John Birch Society. I actually think the fact that the new right has become a significant movement has hurt them."

The first turning point in the group's fortunes occurred in 1964 at the Republican National Convention, when Nelson Rockefeller appeared on coast-to-coast television to accuse the John Birch Society of being both Nazi and Communist sympathizers.

McManus says repeatedly that the John Birch Society has been "victimized" by that and other incidents. That may be so. A negative media blitz against the Society escalated just after it began to establish a sense of legitimacy the public had never before allowed. Since then, the Society has tried to rebuild itself by softening some of its earlier stances while still maintaining that a decentralized powerless national government will cure society's ills.

Because of its newer emphasis on purely political issues, McManus can not understand why the public still associates the Society with book burning. "We've been victimized by book burning," he explains. "I suppose some books deserved to be burned, but it's not our business to go about burning them. It hasn't been done in any organized fashion. It's not a program of ours. Our program is for a better world."

Founded in 1958 by Belmont resident Robert Welch--a native North Carolinian and part owner of the Welch Candy Company which produces Sugar Daddy and Sugar Babies--the Society was named for John Birch, an army intelligence officer killed by communists in China just after World War II.

"Robert Welch decided to form an information service for the American people. John Birch is an educational institution," McManus says. "We preach less government, more responsibility and, with God's help, a better world to live in. We are therefore opposed to communism, but we are just as much opposed to collectivism." McManus defines collectivism to be "big government, small people...socialism."

John Birch's Belmont headquarters are quiet enough. There's a receptionist or two. The carpet has a dull, worm-out and lifeless look. McManus's cramped office is strewn with assorted books, papers, and memorabilia, and on the wall hangs a portrait of Marine General Chester Puller, a Korean War hero.

Outside, most passersby don't even know what organization occupies the plain-looking building, let alone what views the John Birch Society actually promotes. And many of those familiar with the Society don't think about it much.

Yet despite the falloff in membership and the tranquil surroundings, McManus insists that the John Birch Society is thriving. It occupies three full buildings in the Belmont area alone. It has a national payroll of more than 175. Through its Western Islands Publishing Company, the Society prints four magazines, each with circulation hovering around 45,000. McManus one of the few official spokesmen for the Society--writes a syndicated column published in more than 100 county newspapers, although few big city papers run "The Birch Log." Recently, McManus has appeared on CBS's "Nightwatch" and is also scheduled for "PBS Latenight."

"Latenight" produce: Bill Pace says he asked McManus to be a guest on the show because, "We haven't heard from them in a long time. Their being on the show is more of an update. We are always looking for groups which are controversial in nature."

Although definitely less controversial than 20 years ago, the Society still cites a membership of somewhere in between 60,000 and 100,000--but it will not reveal its historical records to show whether it has increased or decreased. Despite the sizable number of Birchers, most probably remain within the organization only a short while, and there is a high attrition rate, according to Leonard Zakim, a spokesman for the Jewish Anti-Defamation League, which monitors the group. Most of the Society's membership is concentrated in the Rocky Mountain states, the South and California.

In the Rocky Mountain region, the people there "are closer to the soil," McManus suggests.

In moderating its earlier racial and social postures, the Society has played up its dreaded fear of a powerful centralized government. "Power corrupts, and absolute power corrupts absolutely," McManus dictates. Because of its basic distrust of government and the people who compose it, the group maintains that government-sponsored activity should be curtailed as much as possible.

"Government has no right to do what no individual has no right to do. No individual has the power to reach into my pocket, and put the money into another person's pocket," McManus contends, adding that the Society feels that as much as 75 percent of government activity is unethical. When asked what the government can do and be ethical at the same time, McManus says only "providing for the national defense."

Other political and philosophical viewpoints on which the Society has built its reputation include:

*Belief in a "conspiracy for power" among most of the nations of the world, a conspiracy enmeshed with a growing communist atmosphere in government and business. Communism is "built and sustained by the West...Communism is controlled and financed by the West, propagated by Wall Street."

*Adamant opposition to "imposed" equality. On the Equal Rights Amendment. McManus has been quoted as saying: "Imagine a woman POW. She would rather make 300 dollars a week as a secretary...The ERA is basically an attack on the family."

*Advocacy of a literacy test for voters. Interviewed by the magazine Reconstructionist, McManus said "we don't feel just anyone should be allowed to vote."

*Strict stances against gun control. "You not only have a right, you have a duty to be properly armed...What else defends you against government? The Second Amendment gives all the other amendments teeth," McManus says.

*Denunciation of the Supreme Court as, in McManus' words, "terrible, a total abomination. It has initiated and continued government intervention into many aspects of our lives where it just doesn't belong." Before the historic desegregation case of 1954. Brown vs Board of Education, racial problems were "being broken down through good will and a recognition of justice. "The United States military was segregated in World War II, but then [racial barriers] were broken down. There was no fanfare, then."

*Strong religious fundamentalism. An atheist "denies the heritage of our country. [The people of the United States were] endowed by the Creator with certain inalienable rights. This is a fundamental premise of our nation," McManus says.

In its assault on America's national government, the Society has at different times called for elimination of Social Security, discontinuation of publicly funded schooling, and vast cutbacks in social spending.

At times McManus seems to echo the views of President Reagan. He argues that "as soon as government gets involved in welfare programs, at least 100 times more people get welfare than actually need it. The needy should be taken care of by private charity. "But, as is the trend among ultra-right groups, the John Birch Society believes Reagan is not a "real conservative."

In one of his syndicated columns, McManus contended that "the man who lambasted Jimmy Carter for $200 billion in federal red ink after four years now presides over that much deficit in a single year. Conservatives who still believe in the truth of Ronald Reagan's government is the problem' have been humiliated and rendered leaderless."

Because of such unorthodox political views and accusations against the government and its officials, the Society asserts that Washington conducted a national and "vicious smear campaign' against the John Birch Society in the 1960s.

"We pointed our fingers at all the powerful people in the United States," he says. "There was a deliberate attempt to make the John Birch Society look lousy. How can you make us more lousy than calling us racist, anti-Semitic, pro Nazi, pro-KKK and other junk like that?

"And believe me, the people who are most upset by this are our Jewish and Black members."

McManus acknowledges, however, that the Society has very few Jewish or Black members.

Such criticisms were, however, no doubt warranted two decades ago. In Bulletin, published by the John Birch Society in 1965. Robert Welch wrote that"...there comes a period of some 40 years when an abnormal percentage of the Communist Conspiracy was of Jewish ancestry. And these traitors to their race--as well as to mankind--worked and schemed and plotted to have themselves hated, not as Communists, but as Jews."

Even McManus concedes that at "one time" anti-Semitism pervaded the John Birch Society. But he adds that anyone who accuses the JBS today as being anti-Semitic is a downright liar. The ADL, wouldn't say that any longer."

And the Society does appear to have cleaned up its act regarding anti-Semitism and racism Spokesmen for both the ADL and the NAACP attest to that.

Maybe that's all in vain.

One Belmont citizen says. "About 20 years ago, there were a lot of Birchies here. They stirred a lot of interest, then, but now no one even thinks of them."

But the members still persist, convinced that if they lose, havoc will reign. "Our strategy is to inform society so they choose better leaders. If we're successful, then the trend towards bigger government will stop." McManus says, "If we're not successful then there will be a communist style government in the United States."