PARADES IN NEW YORK City are always an extravagant affair--from ticker tape parades for astronauts to the Macy's Thanksgiving Day Parade featuring every cartoon character from Betty Boop to a Mutant Ninja Turtle.

But the politics of who gets to march in parades is a lot more serious. While the public lines up on Park Avenue to buy hot dogs and listen to high school bands, those marching in the parade have more at stake. For some, participating in a parade like the St. Patrick's Day Parade is an expression of cultural pride. For the Ancient Order of Hibernians which sponsors the parade in New York, this is certainly true.

For the Irish Lesbian and Gay Organization (ILGO), this is also true. But they aren't allowed to participate this year and are suing for discrimination.

JUDGE Rosmarie Maldonoando of the New York City Commission on Human Rights recently denied a motion to dismiss discrimination charges against the Ancient Order of Hibernians, a fraternal Roman Catholic organization. The group will now have to defend itself in court.

Regardless of the decision that comes down, we should see the Hibernians' attempt to keep the ILGO out of today's parade for what it is: a denial that homosexuality exists in its ethnic community.

The conflict surfaced when the Hibernians attempted to exclude the gay group from the parade, arguing that it was their right as a private organization to do so. The Hibernians contend that their basis of discrimination is that homosexuality contradicts the teachings of the Catholic Church.

The fraternal organization also states that the ILGO was excluded because its application never made it to the top of the waiting list. And members of the ILGO, the Hibernians continues, demonstrated inappropriate behavior when they "fondled" (hugged and kissed) each other in last year's parade.

THE LEGAL QUESTION is whether the Hibernians have a legitimate right as a private organization to discriminate in accepting applicants for the yearly parade. Though the fraternal order points to logistical problems--such as late applications--as reasons for denying the IGLO's request, their refusal is clearly a function of discrimination. There is new evidence which suggests that another Irish-American organization, the F.B.I. Emerald Society, was admitted to the parade although its application was not in the waiting list.

THE REAL ISSUE, however, is not the legal right of the Ancient Order of Hibernians to discriminate, nor is it the opposition of the Catholic Church to homosexuality. The ethics of discriminating against a minority group simply because it follows an alternate lifestyle is the relevant question.

As the dispute progresses through the court system, the Hibernians' true motive becomes clear. Their desire is to check the ILGO in order to prevent the spectacle of a group of homosexuals--identified as Irish--parading down Park Avenue. And the Ancient Order has attempted to deny the existence of homosexuality by preventing some of its representatives from marching in the parade.

There is a nostalgic idealism in the Hibernians' desire to conceal homosexuals within their community when most Americans realize that homosexuality is a reality everywhere. Their reaction is analogous to parents' disbelief--"Not in my family!"--upon learning of their child's homosexuality.

But there should be no embarrassment in acknowledging that homosexuality exists within one's ethnic family. In their myopia, the Hibernians have ignored the right of fellow human beings to choose a lifestyle and to be honest about that choice.

THE HIBERNIAN attempt to stop Irish homosexuals from presenting themselves to their ethnic community and to the whole of New York merely exacerbates the common tendency of heterosexuals to deny the existence of homosexuality.

But their efforts--however misguided--could have favorable results for the gay and lesbian communities. Discriminating against the ILGO has focused substantial attention on the gay issues and has given the organization the public recognition it has been seeking.

Did this legal battle stem from mothers' fears that their children would choose a homosexual lifestyle after seeing ILGO's parade on St. Patrick's Day? The Hibernians' action underlines an ignorance extant in this country, the result of Americans preferring to shut their eyes to reality.

However uncomfortable for the Ancient Order of Hibernians, the ILGO appearance in the St. Patrick's Day Parade will bring onlookers closer to accepting homosexuality as an American reality.

The Hibernians have consistently deferred to the teachings of the Catholic Church as justification for their feelings. Perhaps the Ancient Order of Hibernians should view the debacle in a different light:

The Catholic Church opposes homosexuality, but does it condemn discrimination?