Even before he played tennis with Jacqueline Kennedy, marched alongside the Rev. Martin Luther King Jr. and riled J. Edgar Hoover, the Rev. Richard McSorley led no ordinary life.

He was one of 15 children born into a strict Catholic family in Philadelphia, eight of whom became nuns or priests. He was a prisoner of war in a Japanese camp during World War II and ate worms to keep from starving.

Ever since his three years and three months in the prison camp, McSorley has been an activist, in the throes of the day's crisis. In the 1950s, he joined the national campaign against racism, beginning first in segregated St. Mary's County, Md. In the 1960s, he stirred college students from coast to coast to defy the Vietnam War. More recently, he lived with Mitch Snyder and other advocates for the homeless at the Community for Creative Non-Violence, and was arrested for protesting apartheid, the MX missile and nuclear weapons.

Now, at 76, McSorley is at it again: writing and lecturing against the U.S. buildup in the Persian Gulf and inspiring college students to do the same. He is advising conscientious objectors around the country, writing Congress and scores of newspapers, and encouraging students to join weekly White House protests and the national anti-war marches scheduled for later this month.

In December, McSorley helped Georgetown University students coordinate the Persian Gulf crisis teach-in that drew 500 students. The crisis also has recharged his decades-old battle to eliminate the Reserve Officer Training Corps from college campuses.

"Very few people pour themselves totally into causes, especially unpopular causes. McSorley does," said Rabbi Eugene J. Lipman, former leader of the District's Temple Sinai congregation and one of the religious leaders who lobbied with McSorley against the U.S. air strikes in Vietnam. "He was a student hero in the 1960s and into the '70s; probably still is."

From 1961 to 1985, McSorley taught "War and Peace," a theology class at Georgetown that discussed the morality of war. Now, he is director of the one-man Center for Peace Studies on campus, and is busy writing his autobiography.

"His office is becoming more active these days," said Jenny McNulty, a Georgetown sophomore who has become active in the peace movement. "He's an inspiration to a lot of us."

"He used to say, 'Don't work at all, if you're going to do something that isn't good for people,' " recalled Tara Duffy, who was just out of college, aimless and feeling that life had little meaning when she met McSorley six years ago. "He thought it would be better to do nothing than to work, for instance, for a developer who was terrible to tenants. He had a major impact on me."

Shortly after meeting McSorley, Duffy decided to become a teacher, working with youths in the slums of Chicago and the South Bronx in New York. Now she teaches immigrant and minority college students at National-Louis University in Chicago. "His appeal is his simplicity," Duffy said. "He doesn't try to impress people with well-known names or complicated terms. He talks simply about peace. My friends call him the 'holy man.' "

Others call the tall, wiry white-haired man less complimentary names: simplistic, impractical, single-minded. Some colleagues say privately that he has an unrealistic message of turning the other cheek, of eliminating weapons and of preaching that love and faith -- not guns and tanks -- could conquer even the likes of Hitler.

"Some people would say that he oversimplifies issues of war and peace," said the Rev. Robert Drinan, a former member of Congress and a Jesuit priest who lives along the same corridor as McSorley in the dormitory-like quarters set aside for priests at Georgetown.

"But we need people who are single-issue, uncompromising," Drinan said. "The rest of us can get lost in all the complexities that make it hard to take a stand. He is a true believer. He never gives up."

McSorley has never worried about being popular or in favor with church hierarchy either. During a 1969 congressional hearing on un-American activities, when a Republican congressman from Iowa asked McSorley why he needed to wear a nuclear disarmament pin in addition to his clerical garb to convince people that he was for peace, the priest didn't gloss over his disagreements with the church.

"The reason is because, since the time of Constantine, 312, the Roman Catholic Church and the Christian Church has identified itself with killers throughout centuries," McSorley told the committee. "We have bypassed the laws 'Thou shall not kill' and 'Love your neighbor,' and we have been identified in every age in history with all the leaders of armies, even Hitler, and it is about time that we started identifying ourselves with the love ethic of Jesus, whom we profess to believe in."

He has never minced words about the military either. "And if anyone thinks it's unfair to the military to compare them to prostitutes, I reply that it may be unfair to the prostitutes," he wrote in one of the hundreds of articles he has written on the subject. "Prostitution does not threaten the survival of the world. Prostitution is not supported by taxpayers' money and the power of the Pentagon."

These days, Georgetown University is increasingly filled with wealthy, conservative students, a sign of the times and financial aid cutbacks, McSorley says. But he is heartened, he said, because of the growing interest in anti-war activities by the student body. "When Georgetown gets going on an issue that isn't conservative, you know the whole country is going that way," he said, speaking in the soft, low voice that is his trademark.

"I've been at many demonstrations with him, from the civil rights movement to the anti-war movement," said peace activist Philip Berrigan, who was arrested last Sunday for pouring blood and red dye in a White House fountain to protest the U.S. policy in the Persian Gulf. "He was a friend of the Kennedys', but he always remained very simple. He never got caught up in money or prestige."

McSorley was a 24-year-old seminarian who had volunteered to work at the Jesuit mission in the Philippines when he was rounded by the Japanese. He was imprisoned 75 miles south of Manila five days after Pearl Harbor. Along with 2,500 other starving Americans, he was rescued by paratroopers in 1945.

A year later, he was ordained a priest at Woodstock College in Maryland, where he also received a graduate degree in philosophy. His first assignment was to a rural Maryland parish that segregated black and white parishioners at the communion rail.

There he became involved in the civil rights movement, which eventually led him to march with King throughout the South.

In June 1961, McSorley arrived in Washington. Through tennis, he then became a friend of the Kennedys'.

"Robert Kennedy's secretary called over to Georgetown and asked if I could help arrange tennis instructions for the kids," said McSorley, who had just been made the tennis coach. autobiography The tennis lessons soon expanded to study tutorials for the children, and for about three years when Robert F. Kennedy was U.S. attorney general, McSorley spent most evenings at Hickory Hill.

After President Kennedy was assassinated, McSorley got another call from Ethel Kennedy. "She said we're advising Jackie to get out of the house, she was depressed. They asked if I could come over and play tennis with her to cheer her up."

"He was wonderful because he always talked to us at the dinner table," recalled Kathleen Kennedy Townsend, a daughter of Robert and Ethel Kennedy who now works for the Maryland Department of Education in Baltimore. "I remember him talking about man's inhumanity to man and about how horrible war was. I think he thought we should know these things. We were living a fairly well-off life over there in Virginia, and he wanted us to know how others died and suffered in gruesome, horrible ways."

What McSorley saw in the wartime prison camp is never far from his thoughts. Regarding the Middle East crisis, he said, "All those who support this war are trying to make rational what is irrational, dehumanizing. Violence begets violence. We can settle our differences without killing one another."