Less than a year after the events that turned "TV evangelist" into a synonym for scandal, the annual meeting here this week of the National Religious Broadcasters attracted what officials said was its largest crowd in its 45-year history.

An estimated 4,000 broadcasters and their spouses turned out for the five-day meeting that focused as much on politics -- virtually all of it Republican -- as on the electronic media.

In addition to President Reagan, every Republican presidential candidate except Alexander Haig and Pierre (Pete) du Pont addressed the convention.

David Clark, bankruptcy trustee of the PTL television ministry who was also convention program chairman, denied responsibility for the absence of Democratic candidates. "The Republican candidates all invited themselves," he told a questioner, adding that "we did invite Pat Robertson, but that was before he was a candidate."

In a workshop on religious factors in the 1988 presidential elections, University of Virginia sociologist Jeffrey Hadden, a longtime student of religious broadcasting, predicted that the Christian right would play a major, if not determinative, role in the election.

"Every major Republican candidate has viewed this convention as an important campaign stop on the political trail," he said.

Hadden predicted that the Robertson campaign, generally viewed as an unknown factor by political experts, would be far more successful than is generally believed.

"By the end of this month, I think the skeptical press will realize that the Robertson candidacy is for real," he said.

Noting the millions of dollars the former evangelist has raised over the years to support his TV efforts, the sociologist said that "fund-raising skills as a broadcaster are transferable to a political candidacy."

Hadden called Robertson's drive last year to get 3 million signatures on petitions urging him to run "one of the most important political strategies of modern politics" by providing "a national list of voters favorable to the candidate."

"All over America," he continued, Robertson people "are working to expand that list" state by state and congressional district by district.

"I think we are in for one of the wildest campaigns of any political season," Hadden said. In a reference to Robertson's religious ties to his boosters, he added, "Spiritual blood is thicker than political water."

At the same session, Robert Dugan of the National Association of Evangelicals agreed that "the religious factor could be determinative for 1988."

He said his organization, which represents the moderate stream of evangelical Protestantism, "has been wooed and approached by the Republican Party and candidates."

In 1980, he said, the Republican platform committee invited evangelical leaders to a two-hour meeting and dinner to discover what issues were important for evangelicals, he said.

By contrast, Dugan said, repeated efforts by the religious group secured "five grudging minutes from the Democratic platform people."

In a news conference during the convention, Clark, appointed by the federal bankruptcy court as trustee of the scandal-ridden PTL ministry, announced that he had filed on behalf of PTL a civil suit against Jim and Tammy Bakker and their former associate, David Taggart.

The suit seeks to recover nearly $53 million that Clark said was lost through unjustified compensation to the three persons, cash advances on PTL credit cards and mismanagement.

Bakker has repeatedly said he and his wife have only a few thousand dollars. Asked if he believes the couple has funds hidden away, Clark, noting the millions paid them in their last year at PTL, pointed out that they "had their housing supplied, five autos supplied, all the food, a housekeeper and private secretary . . . .

"I don't know where the money went, but I intend to try to find out. The {PTL} ministry sorely needs it and we intend to find it . . . . We want to hold him accountable for the misuse of the ministry, which is fighting for its life at this moment."

Clark said that in a recent poll of contributors, "12 or 13 percent said they would give more money if Jim Bakker came back; 62 percent said that if Jim came back they'd never give another nickel; the rest were either neutral or negative" toward Bakker.

In addition to the civil suit filed this week, the IRS is conducting an investigation and seeking to recover unpaid taxes. Clark said the current overseers of the ministry are trying to persuade the agency to target Bakker and Taggart rather than the PTL.

"What is owed IRS we believe Mr. Bakker was responsible for," he said. Bakker and Taggart "used the ministry for their profit . . . . We feel the IRS should go after the persons who mismanaged the funds," he said.