At a Dallas gathering of 15,000 conservative Christians in the autumn of 1980, as presidential candidate Ronald Reagan sat center stage, evangelist James Robison, a fiery, red-faced orator with a Bible clenched in his upraised hand, thundered that it was "time for God's people to come out of the closet and the churches and change America."

Like some of the groups that left the closet ahead of them, the conservative Christian political movement has discovered that changing America means, to some extent, being changed. Success has caused new tensions within the ranks, tugging the faithful in different directions, producing new potential leaders, alienating old ones.

Millions of the white, right, born-again faithful have answered the call since 1980. The naive ad-hoc troops of those days have in 1984 become an organized, recognized political force in the Republican Party, and some of the electronic preachers who lead them have become familiar figures in the temples of secular power.

Part of the genius of the American system, however, is its ability to embrace and domesticate seemingly radical forces for change even as it responds to them.

"The first term earned us the right to be heard," says Cal Thomas, an official of the Moral Majority. "In the second, we have to earn the right to be followed."

Accordingly, television evangelist Jerry L. Falwell, founder of the Moral Majority and acknowledged "pope" of the religious right, is moving deliberately to take the hard edges off his public image and reach out to a broader American audience.

Many of his critics agree with a Democratic strategist who said, "Falwell's got a lot of work to do if he wants to be perceived as a moderate."

Still, Falwell has softened his position on abortion, in order to "get something through Congress ," says he considers his former nemesis George Bush a fine presumptive heir to President Reagan, is contemplating a massive mobilization of the faithful to send food and medicine to the starving in Marxist-led Ethiopia and is calling on church people to do more to help the poor. He is even proposing to "liberate fundamentalist women" in 1985 -- at least within acceptable conservative limits.

And while some of the secular New Right political leaders, who helped bring the religious right into politics in the first place, have criticized Reagan for failing to champion ultraconservative causes, Falwell has not.

The Rev. Bob Jones, another leading fundamentalist and president of Bob Jones University, wants to pull the movement back to its old traditions. He has called Falwell "the most dangerous man in America" and denounced his political activities as "spiritual fornication."

Just over a year ago, a fundamentalist gathering at Bob Jones University voted to condemn Falwell's strategy of political involvement for compromising the faith.

Falwell responded to Jones' charges by saying that he is indeed "dangerous -- to liberals, humanists, abortionists, homosexuals and the like -- but certainly not to Bible-believing Christians." A Falwell aide dismissed Jones' followers as a small minority.

Jones is of the old fundamentalist school -- to which Falwell once subscribed -- that sees politics as akin to deviltry, a distraction from a proper concern with eternity, and a corrupting influence.

"We believe that the saving of America's morals is a mere cosmetic treatment of the deeper problem of sin, . . . that moral reformation is not the mission of the church but, instead, the preaching of the saving grace of Christ," the Fundamentalist Baptist Fellowship said in a resolution critical of Falwell.

Few observers expect Falwell, who combines media sophistication with strong fundamentalist credentials and a thriving institutional base, to be daunted by Jones' assaults.

Tony Podesta, president of People for the American Way, set up to combat the Moral Majority, said the Falwell-type leaders "have moved the lion's share of the fundamentalists into the world and into politics . . . . We welcome their move toward the center."

But, he added, there are still two Jerry Falwells: the moderate fellow who appears on "Good Morning America" and the old-time fire-breather who still talks about "satanic plots" to his religious audiences.

Most students of conservative Christians predict the believers will follow their activist preachers.

"The key to where most conservative religious voters are going to go to a large extent depends on their ministers: are they going to stay involved?" said Richard A. Viguerie, who publishes the Conservative Digest and chairs the Populist Conservative Tax Coalition. "I think they are. I think the leadership has crossed the Rubicon."

Internal dissension in any movement, he added, "is a sign of your strength, not your weakness." He compared this movement with the black community after its civil-rights successes -- a force, but with splits and disagreements at the top.

"When you're small, in the foxholes, everybody bands together," he said. But once a movement is successful, it can "afford the luxury" of internal disputes.

This syndrome also has overtaken the electronic ministries.

While a few veteran evangelists once had the field to themselves, the competition has proliferated and the audiences are increasingly fragmented, according to Christianity Today.

Several studies have shown that religious broadcasters and secular journalists were guilty in 1980 of careless use of statistics regarding the size of the electronic audience, exaggerating or discounting them. The best estimates put them between 10 million and 20 million, and experts believe that they probably have peaked.

However, to reach more viewers, some religious broadcasters are adapting commercial formulas. USA Today reported this year a proliferation of Christian soap operas, game shows, even situation comedies "to reach viewers turned off by a religious hard-sell and incessant money appeals. "Political Dynamics Still at Issue

Democratic strategists, searching for ways to woo back the Southern vote and especially that of white Protestant males, argue that the loss of Reagan as a rallying point and the credibility he has lent the religious right could be a serious blow to their effort, just as it generally is expected to be to the Republican Party.

The dynamics of the conservative Christian political engagement are still at issue.

An aide to Rep. Tony Coelho (D-Calif.), chairman of the Democratic National Campaign Committee, contended that conservative Christians, like the rest of the electorate, primarily vote their pocketbooks and their patriotism -- not their religious values. He also foresees general aversion to the "extremist agenda" the Republicans adopted in their platform in Dallas last summer -- "even in the South."

"The issues that hurt us in the South this year were patriotism and the tax increase" proposed by Democratic presidential candidate Walter F. Mondale, he said, adding that in 1982, during the recession, "we won a lot of seats in the South."

Liberal former senator George McGovern (D-S.D.), product of a midwestern fundamentalist upbringing who lost his seat after being targeted by the New Right and Christian Right coalition, said he believed that a sizable portion of the conservative Christian vote is lost "forever" to the Democrats.

"But if they could get a third of them again, that wouldn't be too bad, and I think that's doable" mainly through the strength of Democratic local organizations, he said.

The religious right has had mixed success with aggressive, negative assaults on the opposition, Bible "score cards" that rate them on the religious-issues agenda and "send another Christian to Congress" pitches. Such efforts backfired in some states, particularly one in Michigan aimed at a Jewish incumbent, but succeeded in Georgia and some others, Democrats noted.

Polls have shown that Americans generally do not object to members of the clergy and religious organizations discussing the moral implications of public policy, but that they strongly object to their working directly to defeat candidates or to enact specific legislation.

Some concluded after the 1982 elections that the religious right was a flash in the pan. But Republicans and Democrats alike credit the movement with a much more sophisticated organization this year than in 1980 and a political presence that has outstripped the secular New Right political organizations that helped produce it. The religious right played an especially significant role in key Senate races in North Carolina and Texas, where they registered and turned out large numbers of conservative Christian voters.

Speculation now focuses on how the religious right and the aspiring Republicans of 1988 will handle one another.

Reps. Jack Kemp (R-N.Y.) and Newt Gingrich (R-Ga.), Sen. William L. Armstrong (R-Colo.) and U.N. Ambassador Jeane J. Kirkpatrick are listed by the Moral Majority as among those with the credentials to compete with Bush for the support of religious-right voters.

Some conservatives suggest that Bush and Kemp aren't sure how to handle the religious right and, as the National Review put it this month, that neither "has the talent or skill of Ronald Reagan" in attracting both them and the baby-boom Yuppies -- young urban professionals -- who are put off by their social agenda.

"They clearly are a vibrant and growing force," said an aide to Kemp. "Anybody who wants to work within the process is more than welcome . . . .[Kemp] does not support 100 percent the views of the Christian right but is in sympathy with its thrust and can work with them." Leadership "Like Football Substitutions"

Christian Right organizations, meanwhile, seem to be unforming and re-forming kaleidoscopically.

The Moral Majority, Christian Voice and other like-minded groups recently joined under the umbrella of the American Coalition for Traditional Values (ACTV), a much broader-based replacement for the Religious Roundtable, host of the seminal gathering of evangelists that Reagan attended one brimstone-hot day in Dallas four years ago.

The Roundtable was scrapped, according to Podesta, because of its "bad baggage," such as a controversial statement by an official in one of its forums that "God does not hear the prayer of unredeemed Gentiles or Jews."

(In late 1980, after an hour's discussion with Rabbi Marc Tanenbaum of the American Jewish Committee, Falwell retracted an endorsement of that statement and praised the improving relations between "Bible-believing Christians in America and the Jewish community" in recent decades.)

ACTV is headed by Tim LaHaye, a San Diego evangelist who is moving its headquarters to Washington. It is supported by TV evangelists such as Falwell, Jimmy Swaggart, Jim Bakker and others.

Robison, like some others, has dropped out of the political fray and moved to become heir-apparent to Oral Roberts as leader of charismatic Christians, observers say, and others such as LaHaye and Swaggart are maneuvering to fill the vacuum.

"It's like football substitutions," said one religious journalist, adding that such rapid and dramatic shifts don't happen in mainstream denominational politics.

The big difference between Falwell and some of the other preachers, the writer added, is that "Falwell has a home base, a church, a college. Some of the others do not exist except through TV ministries, seminars and 'crusades.' Their home is wherever they are that night. You never know where to phone them." On the Path to Understanding

Despite the increasing sophistication and prosperity of its members, and their impact on the public-policy debate, adherents of the conservative Christian movement say they remain among the least understood groups in the country.

Some perceive a "blind spot" in the news media toward religion in general and them in particular. There is at least some evidence that this is justified. In a survey in Public Opinion two years ago, half of the members of the media who responded said they had no religious affiliation and 86 percent said they seldom or never attend religious services.

Though civil libertarians and religious groups continue to warn that the conservative Christians want to claim God as a Republican, eroding the constitutional separation of church and state, others are skeptical that they could succeed even if they wanted to.

The Christian soldiers are, in this view, marching along a path well-trod by other crusaders before them.

The dissension over their role likely will lessen somewhat "as they discover -- as the left wing has -- that political solutions aren't that easy," McGovern said. "I think they're going to eventually experience a certain amount of disenchantment" as they learn that "you don't get clear-cut victories. You get a lot of frustration. You get the effort, the struggle."

For now, the various combatants in this latest struggle often seem to echo a lamentation of the English writer Jonathan Swift long ago, that our society has just enough religion for hate but not enough for understanding.

During the days of alarm at the political reawakening of the religious right, in 1980, Richard John Neuhaus, a Lutheran pastor and theologian who now is director of the Center on Religion and Society in New York, told reporters that the leaders of the religious right "are profoundly immature."

"They don't really understand the ethical and philosophical traditions of democracy or how to bring about change in a pluralistic society," he said.

But last week, he said he believed this was changing: "Indeed it seems there has been more growth on the Jerry Falwell side than on the Norman Lear side."

Lear's followers, he added, "are still shouting, 'Falwell is coming! Falwell is coming!' which is not very helpful. The religious right has now demonstrated it is a continuing and permanent community among all the communities that make up this pluralistic society of ours. I think it's incumbent upon the liberal mainline to be much more forthcoming -- or, as they would put it, ecumenical."