The annual convention of the National Religious Broadcasters Association, with Anita Bryant as a featured participant, opened here last night, and hundreds of demonstrators marched on the Washington Hilton Hotel where it was being held.

The candle carrying demonstrators, estimated by U.S. Park Police to number about 2,000, apparently were marching in support of homosexual rights and in opposition to Bryant's appearance here.

Bryant, a singer and television personality, rose to national prominence last year when she campaigned successfully against a Dade County, Fla., ordinance that would have banned housing, public accomodations and job discrimination among homosexuals.

Shortly before 8 last night, many of the demonstrators stood outside the convention hotel chanting "Gay Rights Now."

The demonstrators, whose half-mile line of march had tied up traffic on Connecticut Avenue for a time, remained only briefly at the hotel. After a few minutes of chanting they returned to their rallying point at Dupont Circle and disbanded.

Before the start of the convention yesterday, Bryant appeared at a press conference where she proclaimed the need for morality in America.

"I think America today with a million divorces, a million (youthful) runaways, it's no wonder children are going into . . . drugs and homosexuality," she said, after arriving amid bustle, applause, the whirring of cameras and all the fanfare often associated with a prominent politial candidate.

During the afternoon hundreds of Washington homosexuals and sympathizers gathered in a downtown church for a service of prayer and hymns.

"We proclaim God's love for all people, the Rev. Larry J. Uhrig of Metropolitan Community Church land . . . (There are) people in the land whose ways are somewhat different. There are those who would like to see them destroyed."

Among the hymns the homosexuals sang so loudly was "Amazing Grace" with its powerful lyrics - lyrics that Bryant herself was scheduled to sing in the opening session of the broadcasters' convention last night: "Amazing Grace! How sweet the sound. That saved a wretch like me/ I once was lost, but now an found./ Was blind, but now I see."

Bryant is an impressive person - dynamic, sincere, professional. And even, sometimes, diplomatic. A reporter in the press conference wanted to know her personal feelings about homosexuals and she said, "God loves them. I love them. I love them enough to tell them the truth - that homosexuality is wrong, not by my standards but by God's standards . . . I have never had any hate in my heart for any of them as individuals."

She said that if America departs from "God's standards" then, "I believe that we as a nation are doomed."

The key to Bryant's position on homosexuals - which is only the cutting edge of what is becoming a more general crusade in support of her concept of Christian values - lies in her firm belief that homosexuality is a sin. As she says, it is "an unnatural way and not an alternate life style. All you have to do is look at the human anatomy to know that."

She believes, she said, that homosexuals should be saved from their sinning through a process of religious conversion, on a political level, she believes it is her duty to fight against the notion that homosexuals are a "legitimate minority group" that should be granted rights, including the right to teach in schools.

If they teach in the schools, she explained in an interview before her press conference, they will "recruit" children for their cause - an allegation that Uhrig and other homosexuals are granted minority rights, she argued, then by extension society would have to grant such rights "to a person who has a sexual preference for the dead or who wants to have sex with a Saint Bernard."

"She has served two purposes," said Mayo Lee, president of the Gay Activists, Alliance. "She's united the gay community, and she's got people at least discussing gay issues. Because once people discuss them there's nothing to fear about homosexuality."

In the church service yesterday afternoon, Uhrig argued in his sermon that homosexuals themselves, by their fears, have "accommodated the oppression" brought by the nonhomosexual majority.

"On the bottom line most of us are insecure and have a very low self-esteem because we've bought all along what's been said by the rest of the world . . . We bought it all." Now, he argued, it is time to change that, to "proclaim if you will the rights of all people. There is . . . little justice when we live in fear."

Mayo Lee argued in a flier distributed yesterday that, "Children cannot be recruited, converted, or 'catch' homosexuality . . . Statistics show that approximately 10 percent of the adult population is and has historically been predominantly homosexual . . . I find it incredulous that any teacher would discuss their private sex life in the classroom."

He added that, "The events on Sunday are the gay community's way of shouting to the people of Washington that we are being attacked, our freedoms are being threatened . . ."

As thousands of religious broadcasters and their wives descended on the Hilton yesterday, registering and obtaining schedules for the four days of seminars, speeches and workshops, there was a great emphasis on security.

Bryant and her husband, Bob Green, who was constantly at her side, said that there had been death threats against her since she arrived in Washington.

"I was informed by police in both Arlington and Washington that . . . there would be a threat on her life in 1978," said convention security man Clarence A. McGillen. He said homosexuals were "trying to get to her" and that, "the hotel is full of them."

Distirct and Arlington police said yesterday they had received no reports of any threats on Bryant's life.

Mayo Lee said, "There is no truth to that . . . In no instance is it verified (that there has been) a threat on her life. She made more money last year than she's ever made in her life."

Bryant said that her new fame has cut into her revenues as a convention singer. A spokesman for the Religious Broadcasters, Bill Bray, said that Bryant is being paid between $3,000 and $7,500 for her appearance here, but he would not disclose the exact amount.

Bryant also showed a sense of humor.

When spokesman Bray met her for the first time yesterday he said, "Mrs. Bryant, I'm so happy (to meet you.) It's so wonderful, what you're doing."

She smiled and laughed. "You can remain standing," she said.