For a while last winter, Tim Havens, a recent graduate of Brown University and now an evangelical missionary there, had to lead his morning prayer group in a stairwell of the campus chapel. That was because workers were clattering to remake the lower floor for a display of American Indian art, and a Buddhist student group was chanting in the small sanctuary upstairs.
Like most of the Ivy League universities, Brown was founded by Protestant ministers as an expressly Christian college. But over the years it gradually shed its religious affiliation and became a secular institution, as did the other Ivies. In addition to Buddhists, the Brown chaplain's office now recognizes ''heathen/pagan'' as a ''faith community.''
But these days evangelical students like those in Havens' prayer group are becoming a conspicuous presence at Brown. Of a student body of 5,700, about 400 participate in one of three evangelical student groups - more than the number of active mainline Protestants, the campus chaplain says. And these students are in the vanguard of a larger social shift not just on campuses but also at golf resorts and in boardrooms; they are part of an expanding beachhead of evangelicals in the American elite.
Becoming mainstream: The growing power and influence of evangelical Christians is manifest everywhere these days, from the best-seller lists to the White House, but in fact their share of the general population has not changed much in half a century. Most pollsters agree that people who identify themselves as white evangelical Christians make up about a quarter of the population, just as they have for decades.
What has changed is the class status of evangelicals - Protestants who emphasize the authority of the Bible, the importance of a ''born-again'' conversion experience and spreading the faith. In 1929, the theologian H. Richard Niebuhr described born-again Christianity as the ''religion of the disinherited.''
But over the last 40 years, evangelicals have pulled closer in income and education to mainline Protestants in the historically affluent establishment denominations. In the process they have overturned the old social pecking order in which ''Episcopalian,'' for example, was a code word for upper class, and ''fundamentalist'' or ''evan¬gelical'' shorthand for lower.
Evangelical Christians are now increasingly likely to be college graduates and in the top income brackets. Their growing wealth and education help explain the new influence of evangelicals in American culture and politics.
Campus cash: On The Chronicle of Philanthropy's latest list of the 400 top charities, Campus Crusade for Christ, an evangelical student group, raised more from private donors than the Boy Scouts of America, the Public Broadcasting Service and Easter Seals.
Now a few affluent evangelicals are directing their attention and money at some of the tallest citadels of the secular elite: Ivy League universities. Three years ago a group of evangelical Ivy League alumni formed the Christian Union, an organization intended to ''reclaim the Ivy League for Christ,'' according to its fund-raising materials, and to ''shape the hearts and minds of many thousands who graduate from these schools and who become the elites in other American cultural institutions.''
The Christian Union has bought and maintains new evangelical student centers at Brown, Princeton and Cornell, and has plans to establish a center on every Ivy League campus. In April, 450 students, alumni and supporters met in Princeton for an ''Ivy League Congress on Faith and Action.''
Matt Bennett, founder of the Christian Union, told the conference, ''I love these universities - Princeton and all the others, my alma mater, Cornell - but it really grieves me and really hurts me to think of where they are now.''
The Christian Union's immediate goal, he said, was to recruit campus missionaries. ''What is happening now is good,'' Bennett said, ''but it is like a finger in the dike of keeping back the flood of immorality.''
And trends in the Ivy League today could shape the culture for decades to come, he said.
Havens, who graduated from Brown last year, is the kind of missionary whom the Christian Union hopes to enlist. An evangelical from what he calls a ''solidly middle class'' family in St. Louis, he would have been an anomaly at Brown a couple of generations ago. He applied there, he said, out of a sense of ''nonconformity'' and despite his mother's preference that he attend a Christian college.
When he arrived at Brown, in Providence, R.I., Havens was astounded to find that the biggest campus social event of the fall was the annual SexPowerGod dance, sponsored by the Lesbian Gay Bisexual Transgender Queer Alliance and advertised with dining-hall displays depicting pairs of naked men or women. ''Why do they have to put God in the name?'' he said. ''It seems kind of disrespectful.''
Havens found himself a double outsider of sorts. In addition to being devoted to his faith, he was a scholarship student at a university where half the students can afford $45,000 in tuition and fees without recourse to financial aid and where, he said, many tend to ''spend money like water.''
Havens now is living in a house owned and supported by the Christian Union and is trying to reach not just other evangelicals but nonbelievers as well.
The Christian Union is the brainchild of Matt Bennett, 40, who earned bachelor's and master's degrees at Cornell and later directed the Campus Crusade for Christ at Princeton.
To raise money, Bennett has followed a grapevine of affluent evangelicals around the country, winding up even in places where evangelicals would have been a rarity just a few decades ago.
Meanwhile, evangelical Protestants are pulling closer to their mainline counterparts in class and education.
Providence at work: To many evangelical Christians, the reason for their increasing worldly success and cultural influence is obvious: God's will at work.
There were also demographic forces at work, beginning with the GI Bill, which sent a pioneering generation of evangelicals to college. Probably the greatest boost to the prosperity of evangelicals as a group came with the Sun Belt expansion of the 1970s and the Texas oil boom, which brought new wealth and businesses to the regions where evangelical churches had been most heavily concentrated.
The rise of evangelicals has also coincided with the gradual shift of most of them from the Democratic Party to the Republican and their growing political activism. The conservative Christian political movement seldom developed in poor, rural Bible Belt towns. Instead, its wellsprings were places like the Rev. Ed Young's booming mega-church in suburban Houston or the Rev. Timothy LaHaye's in Orange County, Calif., where evangelical professionals and businessmen pushed back against the secular culture by organizing boycotts, electing school board members and lobbying for conservative judicial appointments.
Lately, Havens has been contemplating steps that would take him away from Brown and campus ministry. He recently became engaged to a missionary colleague and began thinking about how to support the children they hope to have. After another year at Brown, he will head to St. Louis University School of Medicine.
Havens looks forward to having the money a medical degree can bring, and to putting his children through college without the scholarships and part-time jobs he needed. But whether he becomes rich, he said, ''will depend on how much I keep.''
Like other evangelicals of his generation, he means to take his faith with him as he makes his way in the world. He said his roommates at Brown had always predicted that he would ''sell out''- loosen up about his faith and adopt their taste for new cars, new clothes and the other trappings of the upper class.
He didn't at Brown and he thinks he never will. ''So far so good,'' he said.
But he admitted, ''I don't have any money yet.''