THE president's sister has come to Jerusalem, and now, standing in the midst of about 25 people in a hotel meeting room, she is conducting her inner healing session:

"Are there any of you here that have a real spiritual need, that want to receive Jesus that can't . . .? Are there those who feel you have emotional needs that need to be met? Does anyone need a physical healing? Does anyone feel the need to receive baptism by the Holy Spirit?"

The president's sister looks coolly around the room as several people - their heads bowed, eyes closed in prayer - raise their hands slowly.

"Holy Spirit," she says in her soothing, breathy voice, "I invite your presence in an even greater way than you've been tonight. Touch that deep center of our hearts.For those who want to be touched with love and have been so hurt by love as a child, Jesus, touch that hurt caused by that mother or daddy or that important person . . . Those filled with guilt because of something they haven't been able to get rid of . . . Lord, you know who they are. Touch their hearts. And let them be free."

Ruth Carter Stapleton's hair is streaked blond. When she is in public, her mascara, eye shadow and lipstick are carefully coordinated with fashionable clothes. People repeatedly tell her she resembles her brother the president, and sometimes she'll smile and say, "Do you really think so?" which only confirms the similarity. When they're grinning, both the president and his younger sister have bold creases from the sides of their noses to the corners of their mouths; at each temple the skin crinkles. They are both trim for their ages (she is 48, he is 54) with little of the puffiness that marks brother Billy.

The similarity between the two is more than physical. Both possess a drive that, in his case, helped win the presidency and, in her case, lifted an insecure, repressed southern Baptist housewife from a suffocating world church and civic groups to a role as minister to the troubled world.

Until three years ago Ruth Stapleton of Fayeteville, N.C., was known only to "born-again" Christians, some of whom counted themselves part of a growing "charismatic movement." Ruth was an unordained minister among these believers who had undergone an extraordinary encounter with what they believe is the Holy Spirit. Her portfolio was her ability to touch lives when she spoke of the fears that had haunted her own life.

As her brother began winning Democratic primaries, Ruth's friends wondered if she'd change her message because of her new notoriety. They wondered if she would talk about her marriage that almost failed, about the depression that drove her to seclusion and a psychiatrist following the birth of her fourth (and unexpected) child. Strangers wondered if she was a prim zealot, some kind of snake-oil-selling faith healer trading on the family name.

For a moment even Ruth wondered if becoming First Sister would alter her ministry; her audiences had always identified with the personal story of her years of quiet desperation. She would tell of that saga to begin her message - the salvation of the Lord can touch your troubled past, which accounts for your troubled present.

Ruth's message included some basic psychology, calling on her listeners to think back on their early lives, to reconstruct the painful memories and let the grace of the Lord dissolve the bitterness. Her strength was a personal warmth that made people want to share with her their innermost feelings. Her personality - nonthreatening, nonjudgmental - meant gays, alcoholics and others accustomed to hearing of hellfire and damnation were attracted to this honey-voiced women who asked about the hurts of their childhoods.

A chorus of critics have followed her career. In her hometown, a daughter once fought with a classmate who taunted her by saying her mother always "has a Bible on one arm and a drunk on another." Ruth's childhood church, the Baptist, look with disdain on the charismatic movement. The political right labels her a "witch," and her association last year with Hustler publisher Larry Flynt won her few friends. But now Ruth is going international, taking what she calls her "ministry of reconciliation" on the road to any country that invites.

Last month she spent a week in Israel as the titular leader of a tour through the Holy Land for about 70 Americans. She distributed loaves and fishes at the place where the apostle Peter cast his net into the Sea of Galilee. Photographers clamored for one more picture. Over her head Israeli fighter jets screamed to the Golan Heights, en route to Lebanon where their sonic booms, reminded troops shelling the Christian suburbs of Beirut that Israel was watching. For a week she walked in Jesus' footsteps. But her presence held as much political significance as religious.

Though she sidestepped questions about her brother's foreign policy, she repeatedly called for prayers for peace. And after her tour group returned to the United States, Ruth traveled to Jordan and Egypt at the invitation of those governments. Before she left Washington, she had huddled with national security adviser Zbigniew Brzezinski; clearly, the U.S. government trusted her ability to engender favorable public relations for her brother. And except for a Los Angeles Times reporter's exaggerated story from Cairo, in which he described her as wearing a "see-through" dress while visiting the Coptic pope and the Pyramids, she received favorable press thoughout the Middle East.

Ruth's trip to Israel was first planned in 1976, so her appearance there during the Camp David summit conference was coincidence.

"When I heard about Camp David, I visited Jimmy," she said. "I said I'd cancel my trip." No, the president assured her, the timing was ideal; she could encourage the people of the Middle East to pray for peace as their leaders negotiated. The addition of visits to Amman and Cairo would balance her visit to the Jewish state.

In coming months she plans trips to India, Africa and Japan. She hopes for a chance to visit Soviet bloc nations. "The strength of the world," she says, "is dependent on emotional stability and mental health," her two specialties. Though some find the hope naive, Ruth thinks that if she can help bring personal tranquility to world leaders, the people would benefit.

Today she privately counsels troubled Washington politicians and White House staffers. In West Germany last year she spoke of spiritual therapy before the parliament and met with Chancellor Helmut Schmidt to discuss her ministry. Only awkward airline connections prevented her from keeping an appointment with Pope John Paul I several weeks ago. At a Cairo tea party last month given by the wife of the Egyptian vice president, Ruth talked about the difficulty of the political life. As the afternoon wore on, a routine diplomatic function involving a half-dozen women very nearly became an encounter session, with the wives of Sadat's lieutenants confiding their personal problems to the First Sister.

Yet if Ruth helps save the world by broadening her ministry, it will not be because of her political acumen. In that department she is frankly naive, asking as she flew to the Middle East if Egypt and Jordan were friendly toward each other, inquiring at another point where the term "Armenian" originated. But though reporters insist on peppering her with questions about whether "you agree with your brother" on political issues, Ruth makes no pretense of being Henry Kissinger with a Bible.

No, if she enjoys success in her global mission of reconciliation, it will be because of enormous personal charm, coupled with the encouragement of friends in high places - the president of the United States and God.

"Now, take a deep breath and let go of all your humanity," she is saying this night in Jerusalem. Her audience is American, tourists who each paid about $1,300 to accompany her through Israel. From the adjoining room came sounds of a televised basketball game; in Tel Aviv the Washington Bullets are losing to Israel's championship team. At Camp David her brother, Anwar Sadat and Menachem Begin are beginning a three-day pause in negotiatons to celebrate the consecutive Muslim, Jewish and Christian holy days.

She commands her listeners: "Every hurt, every person you've ever hurt, every sexual problem you've ever had . . . just LET GO!"

She asks them to think back 20 years, past that to 25 or 30 years earlier in their lives. "Holy Spirit," she prays, "move deep, deep into the deep mind now, 30, 35 years now . . . Pour your deep love into our mind, consume that moment and remove that scar from that life!"

All over the world Ruth Stapleton has friends, most of whom she's met during her ministry of two decades. Her brother's political aspirations didn't surface until 1963, and the names his sister collected in her address book, organized alphabetically by state rather than by name, proved invaluable when "Jimmy Who?" took his early presidential campaign to parts of the nation where he needed to recruit local political captains.

Ruth accumulated those names by spending years speaking to small religious groups around the country and by counseling individuals. Often she became intimately involved in a person's life, such as the time she was awakened in one city by an acquaintance, a devout Catholic, a successful businessman and community leader with a family and a mistress. He couldn't stomach cheating on his wife any longer, he told a sleepy Ruth over the phone. Would she accompany him to his girlfriend's house to help him end his affair?

She did, and the trio spent hours talking, crying and praying until Ruth made everyone breakfast as the sun rose. She is, say those who know her, that kind of person.

Sometimes the voice on the phone will be a stranger's, threatening suicide unless Ruth agrees to talk. She says she never refuses, but because of a crowded travel and lecture schedule, she tries to shift cases to friends who volunteer their help. At her retreat called Holavita ("whole life") near Denton, Texas, some 30 volunteers help answer about 500 letters that arrive addressed to Ruth each week. Many come from some of the 300,000 people who have read her two books on inner healing. "Inner healing is a healing of the emotions, the attitudes within," she explains. "The purpose is to change any negative attitude into a positive one, to remove any negative hang-up such as fear or a feeling of inferiority. Getting to the foot of what causes these feelings of guilt or rejection and dealing with them is the healing. It is another step in the cleansing of the Spirit."

Hers is not a new approach. She acknowledges a debt to Agnes Sanford, an Episcopal faith healer most active in the 1950s who practiced what Sandford called "the healing of the memories." (Neither Sanford nor Ruth are to be confused with American's more theatrical healers, the tent revivalists who shouted, sang and wept between passings of collection plates). But Ruth says she did not fashion her ministry after any one mentor, that her religious background and readings of psychology shaped her theories of "inner healing."

She seeks the child in every adult, asking Jesus to heal psychic wounds inflicted years earlier. Though the emphasis of her ministry is on the soothing of an individual's emotional, psychological and spiritual needs, she sometimes steps into the world of physical healing, praying for a person's ills.

(At Miss Lillian's 80th birthday party in Plains this summer, Billy Carter complained to Ruth of bursitis, in his shoulder. As a joke she placed her hand on his left shoulder and said, "Heal, Billy, heal!" The family prankster pretended to writhe in pain. "It was the other side!" Billy said, and then spent the rest of the evening feigning agony in the shoulder his sister had touched.)

The line between emotional and physical healing is a fine one. Said an American doctor watching Ruth conduct her inner healing session in Jerusalem. "Seventy-five percent of the problems I see as a general practitioner are psychosomatic. Ruth's work sure beats hell out of psychiatry."

Ruth brings her hands in front of her now, touching the fingers together.

From the corner of the room comes a quiet sob.

She decide to move into a prayer for physical healing.

"Jesus," prays Ruth, "move that light into every cell . . By faith, I believe I can be healed! Say that to yourself! By faith, I believe I can be healed, so right now, by Jesus of Nazareth, be healed!"

As a little girl growing in Plains, Ga., Ruth Carter knew an angry God and an overindulgent father. She was a golden girl - bright, pretty, best friends with Rosalynn Smith, who would later marry Ruth's older brother, Jimmy. She was the third of four children whose father taught them, "There's nobody in the world that's better than you are, but there's nobody in the world you are better than." Her nickname was Boop-A-Doop, and today her family still sometimes calls her Boop.

Her religious training was fundamentalist; it took nearly three decades for her to shed feelings of guilt when liquor touched her lips. (Today she occasionally drinks wine or beer in the evening.) Her school was segregated, another fact of life she says took years for her to face without anguish. The Carter children were friendly with neighborhood black children, however, and they were cared for by blacks.

In a forthcoming biography of brother Billy, Ruth describes one of her teen-age babysitter's favorite games:

"The fire would be lit in the bedroom fireplace, and after we had all settled down, there came the magic moment, the event filled with terror and delight," she wrote. "One of us ran over to the light switch and turned out the lights. Then Annie Mae began to chant in a quavering voice which sounded like a voice from the grave, 'All good chillin better gather 'round 'cause there's a good, strange thing's gonna happen tonight.' We huddled together in total darkness, waiting for the spell to his benevolent black sorceress to terrorize us.

"When Annie Mae spoke again, it was a whinning, high-pitched voice. She told us stories of ghosts and goblins that ate little white children who didn't mind, and cursed the folks who worked on Sunday. At the right hair-raising, blood-curdling moment, she fell silent. I could feel my heart and hear my breath. In the silence, Annie Mae quietly strode through the room to the fireplace. We couldn't see her, but we could hear her movements through the darkness of the room.

"Suddenly, we saw a red glow begin to flutter and bob in the fireplace. The glowing light seemed to levitate from the bed of coals and float around the room, darting toward one of us and then another."

The Carter children's babysitter, Annie Mae, would clench the hot coal between her teeth, exhaling on it to make a glow as she frightened her charges. Annie Mae, the Baptist church and the country life imbued the Carter children with a morality based on fear and guilt. Ruth would work to exorcise some of those memories later in life when she found herself feeling sinful "for just living ."

She left Plains after high school for Georgia State College for Women, which she left after two years, the bride of a young veterinarian named Robert Stapleton.

"I had the idealistic view that marriage was the end to all problems," she recalls now. "When school began to be pretty rough (her real ambition was to be a dancer), I became more interested in marriage. If you can't cope with life where you are, then get married and live happily ever after - as everybody who has been married knows, that's an illusion."

Ruth's illusions faded as she gave birth to three children in the first five years of marriage. The young couple had little money when they moved to Fayetteville, where Robert Stapleton had bought into a veterinarian partnership. With one car and babies to care for, Ruth, the popular blond of high school and college, was confined to home. She missed Plains, and when her father died in 1953, when she was in her mid-20s, she grew gloomy.

Finding it difficult to accept her father's death, Ruth sometimes pretended he was still alive. When she'd return to North Carolina from visiting Plains, she'd be sick for a week with a spastic colon and intense back pain. The symptoms lasted for years.

Says Ruth: "When the kids went to school, I moved into the civic life, really moving from one escape to another. I was not introspective because it was too painful. I was the most active member of the church, probably. They used to say, 'Oh, if we could give an award for the woman of the year for all your work, you'd win it every year.' That made me work harder. That was their psychology. I did everything from making the church wreathes to keep the nursery, everything."

At age 29, after the birth of her fourth child, Ruth found the center would not hold.

"All of a sudden," she remembers now, "I said, 'I refuse to live as I've been living any longer. I'm going to get out of everything.' It was an absolute traumatic stopping, and I didn't leave my house for three months."

Actually she left the home for a nearby cabin beside a lake where, undistracted by civic and church functions, she read books about, among other things, religion and psychology. At a friend's urging, she secretly spent a week at Camp Farthest Out, a non-denominational group that runs religious retreats around the country.

"That's when I heard a lot of new things I'd never heard before, such as 'God is love.' To me it was almost sacrilegious to be getting involved with Catholics and other Protestant denominations. It was the worst week of my life. I was in conflict with myself; I spent most of the time crying. There I met Norman Elliott, the psychologist. He could tell this thing that was happening to me; he understood my trauma.

"But his talks were also upsetting me. There were things I'm almost ashamed to talk about now, but even on Sunday morning the fact that he stood in the pulpit with his shirt unbuttoned with a windbreaker on the sleeves rolled up to the elbow . . . Everything had always been so proper in my life. And his relaxed attitude, telling jokes at strategic moments, to me that was very sacrilegious. After dinner, people would take their cigarettes out and smoke. Not many, but I'd been at Baptist retreats with 4,000 people and who wouldn't see a single cigarette.

"I didn't have a breakdown, but I gave up one kind of life for another. I drove to Chapel Hill to see a psychiatrist. In those days it was taboo to go to a psychiatrist. It was almost like admitting insanity. Daddy told us to solve problems within the family. That was a breakthrough, a sign of my healing. The psychiatrist said I was too proper, too secretive. He insisted on group therapy."

Ruth later decided to return to college an she began collecting the bits of information that would eventually comprise the backbone of her preachings, "breaking through the conditioning of what a Southern belle was supposed to be." But she still didn't have the confidence that so marked her older brother.

"I felt I'd fail every test, yet I got As," she says. "It was fear. Jimmy never had this, he just sailed right through, he always knew . . . I had the same drive, but I always thought I'd fail. What almost prevented me from graduating from college was the fear of making an oral report before eight people. I'd run out crying from the room. Finally the prefessor made the class sit facing the wall with their backs to me. It took three tries."

Later, in the mid-'60s, she would feel the same fear when she took the podium in Arkansas to speak before her first religious group about "the life of prayer." She hyperventilated three times; a paper bag placed over her head revived her.

Ruth's children are grown now. Lyn, 27, is a fashion merchandiser with a baby; Scott, 26, is an opthamology student; Patti, 24, works in a bank and raises two children; and Michael, 20, is a college student in South Carolina. All of them but Michael live in North Carolina. These days Ruth says she feels at peace only with her children.

"You know," she confides, "I have no real close friends who are Christians, people whom I can really let my hair down with."

An old friend remembers Ruth saying 10 years ago that, "I don't let myself get close to anyone, because I don't want to share 10 years ago that, "I don't want to share myself with everyone."

Today Ruth says she's living four lives.

"First there's my ministry, then Jimmy's sister, which opens me up to critism and attacks I wasn't open to before. It's hard to adjust to the fact that no matter who I'm with I'm elevated because I'm Jimmy Carter's sister. Then there's the feminine woman, the spontaneous, light-hearted, flippant, fun-loving person. This I have to temper. Fourth, I'm a mother. My children are my best friends. They fulfill the aloness I feel as Jimmy's sister. I feel more aloneness than anyone can know. Only with my children can I be natural, excessive, prayful, tearful. That's why I have to go home often. That's the center."

Her life is upper-middle class; in addition to the lake-side cabin, the Stapletons own a vacation home in Portugal.

The financial books of the non-profit organization that handless her finances, Behold, Inc., are kept by Ruth's husband, Bobby, who recently retired from his prosperous veterinarian practice to travel with her . A 6-foot, 3-inch lanky southerner, Bobby cheerfully admits to his role as his wife's porter, organizer, suitcase-packer and message-taker. "I'm Ruth's biggest problem and her biggest security," he says. "I work on building the walls, and Ruth expands them. That's the way I like to put it."

On the road he tries to shield Ruth from publicity-seekers and others who crowd her. He makes certain she doesn't leave her glasses at a luncheon table, and if someone is clinging uncomfortably to Ruth, Bobby steps in to the rescue. His conversation is homespun, often punctuated with stories of his hobbies-fishing, flying and golfing. While his wife makes no secret of marital problems a decade ago, Bobby is less willing to discuse either his personal or his religious life.

"There have been times when I've been jealous of Jesus Christ," he will admit. "But a couple of months ago a man in Hawaii walked up to me and said, 'I want to thank you. Your wife saved my life three years ago.' You're tired, you're exhausted, she's exhausted, but you hear that and you get up and go on giving."

The Stapletons may be one of the foremost American families when it comes to the experience of speaking in tongues, that emotional rush of unintelligible syllables often experienced by someone undergoing an intense emotional (usually religious) experience. When husband Bobby was born again, he spoke in tongues. When he was about 9 years old, Michael Stapleton burst forth in tongues when, to his surprise, he received for his birthday a mini-bike he'd been fervently praying for each night.

"I experienced speaking in tongues long before Bobby, and that caused problems," Ruth recalls. "It was like I had leprosy." After an inner healing session during her trip to Israel last month, Ruth said her husband, "Bobby, you know I was thinking of praying in tongues, but I was afraid it might turn some people off."

"You mean you can control it?" he asked.

"Yes," she said.

"Ruth in all these years that we've gone out for dinner," said Bobby, "I've always been afraid that at any minute you might just begin speaking in tongues."

Unlike evangelists such as Bill Graham, Ruth Stapleton has neither a corps of aides nor banks of computers to spread her word. She dependson the kindness of others and she receives it. Volunteers help answer her mail; experts seem to materialize at the right moment. Guiding her through Israel, Jordon and Egypt was a California preacher, the Rev. William Steuart McBirnie, who will also lend his archeological training and knowledge of the Middle East to a book Ruth Stapleton is planning on the Holy Land. McBirnie paid his own way as well as the tab for a secretary fluent in Arabic, a photographer and a driver. He is a Reagan conservative whose political radio broadcasts on the West Coast regularly blast President Carter.

Few things please Ruth Stapleton more than such apparent contradictions. For example: in Cairo last month, Ruth learned former Realist editor Paul Krassner was supposed to be in town, having traveled with the Grateful Dead to Egypt for a concert. During a brief tenure as head of Larry Flynt's Hustler magazine, Krassner published an issue of the magazine whose cover suggested there was a picture of Ruth nude inside.

A drawing of a shocked President Carter adorned Hustler's cover. The whole thing was a spoof. Stapleton asked Flynt to fire Krassner, and he did. But on this afternoon in Cairo, she asked if someone could find Krassner to invite him for a talk.

"After all," she said with a smile, "mine is supposed to be a ministry of reconciliation isn't it?" Only the inability to determine Krassner's whereabouts saved him from a dose of inner healing at the base of the Pyramids that afternoon.

"There's a difference between being religious and being spiritual," says Ruth, who prefers the latter. "When we become Christians the rules are not to talk about Jesus more or to get on our knees and pray in front of people more, it's to love more."

The prayer meeting is drawing to a close now, and Ruth offers "point of contact" to anyone who cares to be touched while she prays for a healing. A dozen people raise their hands.

"Jesus is the healer," Ruth says as she moves toward a woman, cradling the woman's face and neck in her outstretched hands. "But at this moment I pray: Jesus Christ, may every cell within her body be united with You to heal her."

She saves the most obviously ill for last, including a man crippled by muscle deterioration. For a week, with help of his wife and other people on the Ruth Carter Stapleton Tour of the Holy Land, he has visited sites of Jesus' healing miracles. Tonight Ruth Stapleton embraces him and asks everyone in the room to join hands in prayer for his healing.

At her first public appearance after brother Jimmy became president, at a stadium in Alexandria, Va., Ruth looked at the front row of the audience to see reporters from major newspapers watching her.

"I panicked. I thought I was going to destroy Jimmy. I didn't know whether I was going to just use theory and other people's examples or my own. It was freezing, and I was sweating." She felt the way she had when she began making speeches; then, she'd return to her motel room to cry, overwhelmed by insecurity. But this day she made the decision not to change her message: "I decided I was going to be vulnerable."

Now, after two years as a very public figure, after seeing her portrait stare back at her from the covers of at least two national magazines, Ruth Stapleton understands the uses to which she can put her fame.

Press coverage is easy to garner. Her family name - in the Middle East almost everyone called her Mrs. Carter - provides her entree to government figures. Abroad, U.S. embassies render what is called "facilitative assistance" by providing visas, itinerary aid and an occasional car.

In Jordan and Egypt she was treated as visiting royalty. Two government helicopters ferried her and her party from Israeli-occupied territory to a sightseeing tour of Petra, the ancient city carved from rose-colored rock in the southern region of Jordan. A feast of mansaf - lamb with rice, parsley, pine nuts and a sour-milk gravy - awaited the group. Ruth joined in the custom of eating the feast from a community platter using only her right hand.

In Amman, King Hussein's sister hosted an elaborate dinner for her. In both Arab countries she stayed at official guest houses and traveled by police motorcade. In Egypt, when her limousine passed near malodorous neighborhoods, an Egyptian aide sprayed the car's interior with room deodorant.

Ruth knows the royal treatment will end when her brother is no longer president. She also knows she has a rare opportunity to take her ministry overseas if she can keep her religious precepts general enough to include Christians, Muslims, Buddhists and Jews.

Each night before she goes to bed, Ruth Carter Stapleton uses her finger to make one sign of the cross above her blankets, another on her sheet. Then the president's sister falls asleepbetween the crosses.