Riding the crest of the wave of born-again evangelical fervor that is sweeping America, more than 2,000 television and radio religion broadcasters are gathering here in the Washington Hilton for the four-day, 35th convention of the National Religious Broadcasters Association.

Singer Anita Bryant will help begin the convention tonight, singing "How Great Thou Art" and "Amazing Grace" in the concert, as Washington's homosexual community stages a series of demonstrations to protest her presence in the city. Former Nixon political enforcer and born-again Christian Charles Colson will show his film on prison reform tonight.

"It's a breath-taking week," predicted NRB public relations man William Bray. "I can't think of anything that shows better what's happening in this country. You'll see a slice of everything - brand new converts like Larry Flynt. Eldridge Cleaver will speak . . ."

And many more. A fantastic cast of characters will gather under the common tent of deep personal commitment to Christ. Besides Flynt, the converted Hustler magazine publisher, and former Black Panther Cleaver, speakers will include marabel Morgan, author of "Total Joy" and "Total Woman;" Labelle Lance, wife of former Carter administration official Bert Lance: British essayist and iconoclast Malcolm Muggeridge, and Catherine Marshall, author of "A Man Called Peter."

Many of the religious broadcasters are among the country's best-known radio and television personalities - Billy Graham with his "Day of Discovery"; Pat Robertson with "700 Club" out of Virginia Beach; "The Oral Roberts Show"; Rex Humbard's "Cathedral of Tomorrow" from Akron, Ohio; Robert Schuller's "Hour of Power"; Jerry Falwell's "Old Time Gospel Hour," and Jim Bakker's "P.T.L. Club" from Charlotte. These are on television.

And on radio: Theodore Epp's "Back to the Bible Broadcast": Billy Graham's "Hour of Decision," and Richard DeHaan's "Radio Bible Class," among others.

Many of the television programs have more than 2 million viewers, According to NRB's executive secretary, Ben Armstrong. By comparison, he said a popular general television talk show might draw 2.8 million viewers.

The increase in popularity of such programs has been dramatic. Then are 150 million radio listeners and 14 million television viewers who regularly tune into such programs, Armstrong said. He said one new Christian radio station comes into being each week and a new television station each month. The NRB's membership has grown in a decade from 104 to 850 member organizations.

The programs vary in style and tone. "Hour of Power," for example, comes on with established anthems and a church service, while evangelists like Bakker and Robertson come on strongly with what Armstrong calls a "charismatic orientation."

This fervor, these programs - all of it grows out of what the evangelicals call a deep new hunger for spiritual values in America today, and an equally deep disappointment with the achievements of mere politics.

"I think the spiritual revival is the kind of thing that has developed since the disillusion of the '60s," said Armstrong. " . . . There's a conservative trend in the country, (and) in the religious field it seems people are getting back to the age-old standards . . . back to Christ-centered religion . . ."

Bob Green, Anita Bryant's husband, said, "The country is turning toward profamily values, or 'Back to the old days.' . . . People yearn for somebody who takes a strong position . . . They're tired of politicians (and) preachers who straddle the fence on moral issues."

Key to much of the revival spirit has been the increase in personal religious experiences - visions of Christ. "The mainstream of what's going on in religion in America today is that people want a personal experience," said Bray. "I mean, they really want a living God."

Evangelists claim as many as 35 million born-again Christians, including the ones in the White House. At the same time, however, many both inside and outside the evangelical movement warn that it must develop a social conscience and avoid the inward-turning tendencies of the 1970s, America's selfishness decade.

The Rev. William Sloane Coffin Jr. of Manhattan's Riverside Church, a social activist and former Yale University chaplain, said he admires the fervor of the new evangelicals. But he added: "I am deeply suspicious of personal conversion that is not accompanied by a change in social attitude. I think that finally Christ asks you to make common cause with suffering."

He likened Anita Bryant to a "Captain Ahab who cannot take the complexity of evil and so tries to confine it into one great white whale which she can then pursue and slay." This was a reference to Bryant's successful campaign against a Dade County, Fla., ordinance that would have banned housing and job discrimination against homosexuals.

Wes Michaelson, former aide to born-again Sen. Mark Hatfield and now editor of what he calls a politically radical evangelical journal, Sojourners, criticized the "superstar . . . mentality" that he thinks dominates the NRB convention and much of the current evangelical movement.

"Cleaver will be there again this year," he said. "They all enter this star complex . . . They are just very culturally conformed (to) society's values of materialism and patriotism and nationalism . . . I don't think a lot of those who are most worshiped in the evangelical stardom have radically reoriented their lives. I don't think they give one the sense of what the life of Jesus would be like in our society today."

Bray conceded that social concern in the movement is "just not visible right now." But he added, "It's growing and coming all the time." He cited Colson's concern with prison reforms as an example.

Of the broadcasters, Bray said: "Part of the theology of this movement is that . . . if you come to God you'll be healed wholly - physically, spiritually and mentally. A lot of these guys preach and teach it and so they have to drive big cars and stuff to . . . demonstrate their success. They're telling their listeners that they've been successful with God."