Paul Popham is an unlikely activist, a man of wealth who finds "gay politics distasteful." For years he wrapped himself in a cocoon of privilege and, like many homosexuals in America, remained invisible. Then, in 1980, his friends began to die.

"I live in New York City; discrimination was always just a word to me," Popham said, as he sat in his elegant apartment talking quietly about AIDS, the deaths of several of his closest friends, and his metamorphosis from Wall Street banker to chairman of Gay Men's Health Crisis. "Believe me, this is not something I asked for. But people were dying and nobody cared. Suddenly, silence was a luxury I couldn't afford."

The image of Rock Hudson languishing in Paris and California hospitals has focused unparalleled attention on the AIDS epidemic. But, for the gay community in America, which for four years has lived with increasing fear of a mysterious and ravaging disease, AIDS has been an affliction that has derailed a decade of progress. Before this crisis, many homosexuals spoke of a new tolerance and growing acceptance.

Now, activists like Popham find themselves fighting for the civil rights they had begun to take for granted.

While gay leaders say their community's response to the crisis has been heroic, they also fear a powerful backlash -- because since 1981, when the disease began to spread among young gay men, acquired immune deficiency syndrome has been affixed with a nearly indelible homosexual identity. More than ever before, AIDS has forced homosexuals to reassess their status in American society.

From Capitol Hill, where lobbying for research funds has been furious, to small suburban communities scattered throughout the nation, AIDS has displaced all other items on the gay political agenda. Motivated by that fear of a backlash as well as of the disease itself, hundreds of local organizations to fight AIDS have arisen and the impact of the disease has been profound. Where once national gay organizations fought bitterly to get the federal government out of their lives, today they are scrapping for a piece of the pie.

"It is a radical change," said Jeffrey Levi, Washington representative of the National Gay Task Force. "We have started to act like a traditional minority group. What AIDS has done is teach gays that the government has a positive contribution to make."

The crisis has given lobbyists for gay organizations unprecedented access to public officials. Politicians who would have no interest in hearing the case for a gay rights bill have been willing to learn about an epidemic of a disease that is almost always fatal and has no cure.

"I cannot discount the tragedy, but I have seen gay life change irrevocably for the better," said Rodger McFarlane, a former New York hospital administrator who has become a leading spokesman in the war against the disease. "AIDS is the most blatant vulgar metaphor for the status of our civil rights in this country. It isn't just that you have no right to housing, but they will actually neglect you to death. All you need is to see one person die and you make the connection from infectious disease to political movement."

Federal spending in connection with AIDS research and treatment has jumped from $2.5 million in 1982 to $96 million this year. Last week, Health and Human Services Secretary Margaret Heckler asked Congress to boost by 50 percent its 1986 appropriation to $126.3 million. Heckler has repeatedly called AIDS the nation's No. 1 health problem, but to the bitterness of many gay activists and public health officals, President Reagan has never publicly mentioned the disease.

Critics of the administration say that although the disease is spreading swiftly -- there is as yet no cure and more than 12,000 cases have been reported so far -- it has never received the attention it deserves from the federal government because almost 75 percent of the victims are homosexual men.

"The Reagan administration was slow to respond to this crisis because it hit the gay community hardest," said Rep. Henry A. Waxman (D-Calif), chairman of the house subcommittee that has jurisdiction over most of the federal AIDS funds. "If this hit the Chamber of Commerce or the Republican National Committee they would have acted with a greater sense of urgency."

But at a House hearing last week, James O. Mason, assistant secretary for health, said that the Reagan administration had left "no stone unturned" in the search for treatment and a cure.

As the crisis grows, medical experts say it could threaten to overwhelm the health care delivery system. According to a recent study by the federal Centers for Disease Control, more than $1 billion has already been spent on medical care for AIDS victims -- most of that in direct hospital costs -- and the figure is expected to top $10 billion by the end of the decade. The number of cases is doubling each year and public health officials say that by 1987 at least 40,000 people will suffer from AIDS. Researchers now believe it will kill more men than died in Vietnam.

To fill the vacuum caused by what gay organizations say was a confused and diffident federal response, organizations such as GMHC have been created. Gay philanthropy has hit an all time high. Last Sunday, a march in Los Angeles raised more than $600,000 for AIDS research and treatment. GMHC raised more than $2 million in the past year and in the District, virtually all work on AIDS has revolved around the Whitman-Walker clinic.

A fund-raising event with Hollywood's most famous stars has been scheduled for next month and could bring $1 million to the AIDS Project Los Angeles.

Gay political activists are working hard to make connections to groups of voters whom they feel should understand their concerns. They are traveling the country, raising money and reminding people wherever they go that discrimination against homosexuals is on the rise since AIDS appeared.

"When I talk to welfare mothers I tell them about the costs of caring for AIDS victims," said David Rothenberg, who is running a tough race in Greenwich Village to become New York City's first openly homosexual City Council member, "and when I meet with AIDS patients I let them know the incredible costs of housing the poor."

Rothenberg said he decided to run for the council because "New York's elected officials were sitting around letting GMHC do the work of the Health Department. Even today they send AIDS patients -- black, white, gay or straight -- to GMHC."

AIDS has become a central issue in his campaign, with Rothenberg accusing 17-year incumbent Carol Greitzer of failing to take any initiative in getting money from the city. If he wins, it will be viewed largely as a victory motivated by the anger of the gay community.

Vic Basile, executive director of the Human Rights Campaign Fund, which lobbies for civil rights protection for homosexuals, says that his political action committee will raise more money in the next two years to help gay candidates and elected officials throughout the country who have been supportive to them, than it has in the past five.

No part of the gay community has been left untouched by the threat of AIDS. In some cities more than half the homosexual men have been exposed to the virus. Every party or meeting has become an opportunity to spread the word that sexual restraint is essential, and that health depends on caution.

Almost every gay bar now has signs that advertise "Safe Sex" -- guidelines that suggest that gay men refrain from using drugs, masturbate freely but avoid anal sex or the exchange of bodily fluids. Efforts to reach out to the black and hispanic gay community, where education about AIDS has been paltry so far, have intensified.

But because so many questions surround the transmission of the disease -- it is generally thought to spread through sexual contact and exchange of blood products -- little that is said can be reassuring to people most at risk.

"You look at the guidelines for Safe Sex and tell me what the hell to do with my life," said one AIDS researcher in Los Angeles. "What it is basically saying is that anything you do can kill you. People are starting to realize we are talking about changes that will affect the rest of their lives."

Everyone involved agrees that to convert the AIDS crisis into an effective civil rights movement will be difficult and that many men, fearful of exposure, have retreated to the closet. Gay leaders say AIDS has greatly increased discrimination against homosexuals and that fear felt by heterosexuals has caused gay men to be treated like pariahs.

"I don't kid myself for a moment," said a senior executive at a Washington public relations firm. "There are plenty of folks out there cheering for my tragedies. I'm waiting for the backlash. First it was some sick joke -- like 'Hey, you guys can't control yourselves, can you.' Now, all of sudden, people are looking at me like I carry a bomb in my wallet."

It is nothing new for homosexuals in America to juggle separate identities and live with contradiction. The District for instance, largely because of the firm support of Mayor Marion Barry, is one of the most congenial cities in America for homosexuals, but like 23 states, it still has a law that forbids sodomy.

Today, although the AIDS crisis has compelled thousands of previously indifferent insulated men out into the streets, it has also caused many, angered and confused at how little is known about how to prevent the disease, to deny their sexuality -- to put padlocks on their closets.

"How do you confront an unprecedented wave of fear and guilt?" asked Larry Uhrig, the pastor of Washington's Metropolitan Community Church, which serves the gay community. "I feel very strongly that the whole issue raises predominantly religious and spiritual feelings. The solution can't just come from science or politics."

Sixteen years after police raided a gay bar in New York City called Stonewall's and started riots that brought thousands of homosexuals out of their closets, gay Americans face a threat that goes to the core of their sexual identity.

"We have to wear down the old stereotypes, and it is a burning irony that it will take AIDS to do that," said Gary MacDonald, executive director of the AIDS Action Council. "But after thousands of men like Rock Hudson, men you thought you knew, go on TV, it's going to get harder to tell those old faggot jokes about swishy limp-wristed men. I'm sorry it's going to take so many dead men to make that point."