Over the past decade, as closet doors swung open, an increasing number of gay men and women stepped out into the public, becoming more visible and influential. They have marched to demand equal rights, and united to respond to the AIDS epidemic.

Bans on job discrimination and other laws that provide protection have made gay people legally acceptable in some corners of the heterosexual community. Now District residents Craig R. Dean and Patrick G. Gill have filed a lawsuit to win still more legal recognition: a marriage license.

Gay people can now be united in holy unions in ceremonies at some churches. What Dean, 27, a lawyer, and Gill, 23, a training and development manager, want is official sanction, and all the rights and obligations bestowed on married couples.

"I want to marry him because I want to show him he is the person I want to spend the rest of my life with," said Dean. "We want to marry for the same reasons anybody else wants to get married -- because we love each other."

Dean and Gill filed their lawsuit against the city government last week after they were denied a marriage license. Same-sex marriage is not legal anywhere in the United States.

Some of the impetus for raising the marriage question comes as a result of AIDS. Partners of gay people who have died have found they have no enforceable claim to property that would have gone to a spouse as a matter of course.

"The protection provided by that one piece of paper {marriage license} determines everything from health benefits from employers to . . . whether or not you get a family discount at the local fitness club," said Ivy Young, director of the Families Project at the National Gay and Lesbian Task Force.

". . . Heterosexual couples that meet in a singles bar and marry three days later have any number of protections not granted to gay and lesbian couples who have been together for many years."

The suit Dean and Gill filed runs headlong into a belief held by many Americans that homosexuality is a sin and should not be recognized by the state.

"The state determines what kind of values it will uphold in our society and our state has traditionally upheld Judeo-Christian behavior such as marriage being between two heterosexuals," said the Rev. Bob Dugan, director of the Washington Office of the National Association of Evangelicals.

Gary Bauer of the Family Research Council in Washington also opposes same-sex marriages. "If you expand it in this area, then there's no place to draw the line," said Bauer, who heads the pro-family, conservative think tank and lobbying group. "On what grounds would we tell a man with three wives that he can't be legally married in the District? Or how about a man who wants to marry his 19-year-old daughter?

" . . . The reason we don't extend these privileges to incestuous or homosexual couples is because we have wanted less of such behavior."

Not all gay people believe legally sanctioned marriage is worth fighting for right now, saying that their relationships shouldn't be forced to fit heterosexual models.

The letter denying the couple a license stated that "the sections of the District of Columbia Code governing marriage do not authorize marriage between persons of the same sex."

While there is no explicit authorization of such unions, there also is no explicit ban in the code. The law in the District "appears to be silent on same-sex marriage," said Claude Bailey, a spokesman for the Office of the Corporation Counsel. Bailey said he could not comment on how the city will respond to the suit.

Laws without specific bans against same-sex marriages have withstood challenges elsewhere. Courts have held that "even if it doesn't say a man and a woman, we all know that's what marriage is," said William Rubenstein, director of the Lesbian and Gay Rights project of the American Civil Liberties Union.

"But these are older cases," Rubenstein said. "A lot of how the District law will be intepreted can be determined by what judge the case gets and the social climate of the city."