In 1980, presidential candidate Ronald Reagan told them, "I endorse you." In the years since, they have settled like a newly awakened angel of conscience on the nation's right shoulder, redefining the terms of public debate.

They are conservative Christians, commonly called the "religious right," or the "new Christian right."

Meet some of them coming to church on an autumn Sunday morning in the flat condo-filled fields east of Dallas:

* Matt Logan, an actor with a troupe called Texas Shakespeare, fresh from a tour, bounding up the steps in designer jeans and sneakers.

* Barbara Montgomery, a Ph.D. from Loyola University, a recovered alcoholic and former atheist, who teaches at a community college.

* Gordon Galloway, a young computer software engineer who can speak trippingly about the second law of thermodynamics. With him is his wife.

* Alton Murrell, a soft-spoken structural steel drafter, with his wife and daughter.

They speak of receiving messages from the Lord as matter-of-factly as those of another American subculture speak of getting in touch with their feelings.

Their faith, they readily acknowledge, makes them suspect in the minds of many of their weekday co-workers and neighbors, who stereotype their kind as bigoted, redneck, often illiterate Bible-thumpers out on the birdsong fringes of American secular life.

In the years following the civil rights crusades and other social upheavals of the 1960s, when it became unpopular to speak ill of blacks and other minorities, the Christian right remained almost the only minority that was socially acceptable to ridicule.

As the nation opens its eyes to them in the 1980s, however, it finds that they are the family up the street or the uncle near Dubuque -- securely entwined through society's mainstream, huge in number and diverse.

In the age of hydrogen bombs and computer dating, "born-again" Christians who take the Bible as God's literal truth account for at least one-fifth of the U.S. population, or about 35 million adults, concentrated in the South and rural Midwest, according to polling experts. Most of them, 85 percent by one estimate, are white.

They subscribe to a rich diversity of doctrinal interpretations, but what unites most conservative Christians is their belief in the divinity of Jesus Christ and in the literal truth of the Bible -- their "symbol of certitude" -- from Eden to Armageddon.

In a society groping for answers in a jungle of moral ambiguity, they seem unambiguously certain they have found "the answer."

The spotlight now shines on their faith because, unlike traditional fundamentalists who shunned politics and concentrated on salvation, the new-style conservative Christian activists decided to risk getting their souls singed in the hurly-burly of secular social and political fights. 'Transitional Group' at Core of Movement

At the core of this movement is a "transitional group" of aspiring lower- and middle-class families on the move from the hearths of a traditional rural past to the job-rich but often terrifying metroplexes of the New South, sociologists say.

Strangers in a strange land, they look to their new-style churches for more than what the old Bible Belt churches could provide -- to serve as a cultural bridge, to shelter them, to give them voice in a secular Babel.

What energizes them is not trendy or trifling.

Their movement sounds the warning that American society, founded on the revolutionary principle of religious freedom, has moved beyond the mere separation of church and state to the banishment of religion and values from public life -- a dilemma described starkly by one theologian as "the naked public square" -- where anything goes.

"I believe the Judeo-Christian ethic is what we're dealing with -- not a movement of wild-eyed conservatives," said Larry Lea, young pastor of the fundamentalist Church on the Rock east of Dallas, one of the fastest growing congregations in the country. "We're dealing with the birthing roots of a nation . . . . What has gripped this society is a returning to roots."

"The country is much more fundamentalist than I think is generally realized," said pollster George Gallup, who has taken a special interest in religious questions. "Nearly half of all the people in this country believe in creationism -- that God created man during the last 10,000 years 44 percent -- and about one-third of the population can be called literalists . . . . They believe the Bible is literally true, word for word . . . . It seems amazing, but it's true."

Conservative Christians are a more complex group than is commonly understood, not so easily pigeonholed, according to those who study them.

Defining them is not easy because the terms are in flux, blurry and overlapping, and are themselves a matter of dispute. They may be called fundamentalists, evangelicals, charismatics, holy rollers, pentecostals, devil separatists, dispensational pre-millenialists, or simply Bible-believing Christians. Many, if you ask, simply say they are "good Christians."

It is impossible to generalize without stepping on someone else's definition, but a sampling of religious and political scholars outlined these major types:

* Fundamentalists -- Tend to emphasize doctrine and belief, read the Bible literally, traditionally have been uneasy with the secular world. They include some who call themselves devil separatists, who don't want to associate even with other Christians who are much involved with the secular world.

* Evangelicals -- May accept fundamentalist doctrine, but tend to emphasize the act of conversion and its importance and the role of taking the message to others. Generally they are considered more worldly, more concerned with social policy. They may be liberal or conservative.

* Charismatics -- May accept fundamentalist doctrine, but tend to emphasize the immediate, emotional manifestation of the spirit -- jumping, shouting, waving their hands in praise, speaking in tongues and faith healing. Adherents include old-line pentecostals, or holy rollers, but also a more modern, younger, better educated group whose practices differ in degree and emphasis.

The temples of conservative Christianity range from the primitive Baptist church in rural South Carolina, which prohibits music, dancing or cardplaying, to huge edifices such as the Crystal Palace of television evangelist Robert Schuller, near Los Angeles, or the First Baptist Church of Dallas, which provides almost total life support for its members.

The largest church in the nation's largest Protestant denomination -- the Southern Baptist Convention -- the First Baptist Church of Dallas owns five blocks of downtown real estate worth about $200 million, has 25,000 members, a 200-member choir, Christian education programs beginning virtually at the cradle, various outreach and social programs, 22 softball teams, two gymnasiums, four bowling lanes, a rollerskating rink, indoor jogging track, two racquetball courts, a Nautilus center and men's and women's saunas.

For those who share their basic beliefs, including the down-and-out and the sick and the troubled, conservative Christians tend to provide the kinds of familial warmth, support and "good works" that are considered the essence of Christian love. However, the rest of humanity, they say, is lamentably bound for hell. Critics Cry 'Moral McCarthyism'

Critics have termed their harsh intolerance of all who reject their beliefs as a hate-filled "moral McCarthyism," with strains of anti-Semitism and racism.

Some conservative Christians acknowledge that the charges have been justified, but say they're working to change, that some of it is baggage carried from a hard-scrabble culture that they've left behind. Their defenders also suggest that their normal human frailties sometimes have been exaggerated because of the naive way they expressed themselves.

The direct impact of the New Right political-religious coalition and of controversial leaders such as television evangelist Jerry Falwell is a matter of debate. But observers on all sides agree that the bestirred broader masses of the Christian right have played a significant role in revising public debate and forcing Americans of every stripe to reexamine the most fundamental questions of ethics and morality.

They have acted as a kind of moral trim-tab on the navigational surface of our history, this view suggests, averting a spin.

About 15 percent of the Americans who voted in 1984 were white, born-again Christians, according to CBS News-New York Times exit polls. A whopping 81 percent of them voted for Reagan, with 19 percent going to Walter F. Mondale. This was a much stronger Republican tilt than in 1980, when they voted 63 percent to 33 percent for Reagan over Jimmy Carter.

Of the white, born-again Christian segment of the electorate, only 4 percent live in large cities. They are concentrated in the rural countryside and suburbs of the South, with sizable numbers in the rural Midwest.

But even in urban Houston, a hub of the U.S. space program, 32 percent of the people -- one-third of the fourth largest city in the country -- believe that the Bible should be taken literally, according to a survey by Rice University.

The "Jesus business" is booming. Radio and TV evangelists reportedly take in hundreds of millions each year.

Since 1980, the budget for all of Falwell's operations, for example, has grown from $58 million to $90 million a year. Membership has tripled. In the last four years, contributions to the group's educational foundation and lobbying arm have shot up from under $400,000 to around $11 million, officials say.

Of the 9,400 radio stations in the United States, 1,043 are religious, including 82 on campuses, according to the National Religious Broadcasters. About 92 of the nation's more than 800 TV stations are religious.

The movement is riding a tide of influence that sometimes has made it appear more unified and threatening than it really is, according to both critics and supporters.

The election and reelection of the most conservative president of the modern era -- "the most evangelical president since the Founding Fathers," as he also has been called -- is a part of this tide. So is the ripening of a new generation of media-savvy preachers. And so is a widespread public recoiling over a spectrum of social ills -- a recoiling that some say has reached critical mass.

The potential is enticing.

"I think America is ready to consider repentence of its sins," said Pastor Tom Vestal of the politically active Mt. Olivet Baptist Church in Raleigh, N.C., which has grown five-fold in the last six years. "It's a great time to be a Christian."

"America stands ready to be mobilized for God, country and the family," wrote sociologist Jeffrey K. Hadden of the University of Virginia and Charles E. Swann of Union Theological Seminary in Richmond, authors of "Prime Time Preachers."

Social researcher Daniel Yankelovich "has his finger on the pulse of a lot of educated, middle-class Americans when he says that while we may personally cherish the changes brought on by the cultural revolution of the sixties, we're not completely comfortable passing this heritage on to our children," they state in a paper prepared for People for the American Way, an organization set up to combat Falwell and other similar ministers.

But they and others say that the preachers themselves have for the most part been too rigid and narrow to accomplish this mission.

Dr. William Sloane Coffin of New York once said in a sermon on the use of the Bible by some conservative preachers, "I would agree that the Bible contains all the answers, at least all the significant ones. But the Bible is something like a mirror. If an ass peers in, you can't expect an apostle to peer out."

The blossoming of the Christian right comes at a time when interest in religious and spiritual matters generally has been regaining lost ground among Americans. The relationship of church and state, and the impact of religious values in the society, fueled considerable debate in the presidential campaign.

At the same time, however, "morality is losing ground," according to a Gallup study published earlier this year for the Princeton Religion Research Center. It cited indications that there is "very little difference in the behavior of the churched and unchurched on a wide range of items including lying, cheating and pilferage."

The study underscored the difference between religious involvement and deep spiritual commitment.

Gallup found little evidence of the religious doubt and rebellion commonly associated with teen-agers. About the same percentage of teens (95 percent) said they believe in God or a universal spirit as in the adult population. Only 6 percent of teens said they have no religious affiliation or preference.

However, the study also found continuing evidence that teen-agers are "not finding the spiritual dimensions they seek" in traditional organized churches. Teens continue to be involved at a higher rate than their elders in new religious movements, such as Bible study groups, Eastern religions and the charismatics.

One teen-ager in five (19 percent) -- about the same proportion as for adults -- says he has had a "born again" experience, has tried to encourage someone else to accept Jesus Christ as his or her savior and believes the Bible should be taken literally. Religious Activism Rooted in History

There is of course nothing new about religious activism on either the right or the left. The original colonies were born in reaction to a world in which statecraft was church-craft, and the country has had a delicate time refining its experiment in religious pluralism since.

There were state constitutions that denied Roman Catholics the right to hold public office. The 1884 anti-Catholic slogan of "Rum, Romanism and Rebellion" backfired on Republicans and helped sweep Grover Cleveland into office.

There were the abolitionist preachers who helped found the GOP, the religious fervor that led to prohibition, and the preachers in the forefront of civil rights, the antiwar movement and other crusades of the 1950s, '60s and '70s. "Jesus freaks" have spanned the decades and the political spectrum.

The activist impulses of the fundamentalist Christians, however, were crushed more than a half century ago, during a time of general religious and social upheaval but most pointedly by a single watershed event.

It was the famous "monkey trial" in Dayton, Tenn., in the summer heat of 1925 -- said to be the first event in the nation covered with live radio broadcasts. In the circus atmosphere of the trial, the nation's press, led by the acidic H.L. Mencken, held the fundamentalists up to a merciless light and left them intellectual outcasts.

Former senator and three-time Democratic nominee for president William Jennings Bryan, the most prestigious defender of the fundamentalist faith, set the know-nothing image of the believers in stone when on the witness stand, he answered a question about his beliefs: "It is better to trust the Rock of Ages than to know the age of rocks."

When pressed by opposing attorney Clarence Darrow on his belief that the Bible is literally true, that Jonah survived the big fish, that Joshua made the sun stand still above the earth, Bryan said, "I do not think about things that I don't think about."

Darrow asked, "Do you think about things that you do think about?"

"Well," Bryan answered, "sometimes."

The fundamentalist movement thereafter splintered into feuding factions, isolated from mainstream conservative Protestant leaders who quickly disassociated themselves from the anti-evolution crusaders.

The fundamentalists fell off the national screen for a time, some thought for good. The main perception of the conservative Christian movement was for decades embodied primarily in the giant revivals of evangelist Billy Graham.

The rise of Jimmy Carter to the presidency brought the phrase "born again" back into the forefront of the political lexicon. But Carter's blend of liberal politics and earnest Baptist zeal made his liberal constituencies uneasy. Moreover, after raising the expectations of the increasingly restive Christian Right, he then brought their frustrations to the boiling point.

They had watched from the sidelines while liberal causes dominated the public agenda: abortion was legalized, the gay rights and feminist movements mushroomed, taxes were used to pressure Christian schools to abide by civil rights laws and national resistance to the communist threat seemed to wither.

As theologian Martin Marty of the University of Chicago put it: "They felt left out of everybody else's liberation." Meanwhile, a foundation for their uprising had been laid by the media revolution, which produced religious television personalities with massive new powers to communicate and raise money.

In 1979, the sleeping lion of fundamentalism seemed suddenly to leap to its feet, fed up.

Falwell formed the Moral Majority, and the political whiz kids of the New Right completed a circuit to the electronic evangelists. Political hit lists, voter registration drives, grassroots mass meetings, lobbying arms and mailing lists blossomed on behalf of their pro-life, pro-moral, pro-family, pro-America line.

The press and the pundits began to pay attention and scratch their heads, wondering where these folks had sprung from.

TOMORROW: The transitional generation