For 20 years, St. Catherine of Siena Catholic Church has attracted some of the area's most influential people to a secluded sanctuary in a grove of evergreen trees on Springvale Road in Great Falls.

Doctors, lawyers, bureaucrats, technology executives, politicians, artists and intelligence operatives have found solace and unity in traditional Masses and in the deep-seated piety of the church's 4,000 members. They also have enjoyed the anonymity of worshiping in a quiet parish 20 miles from downtown Washington.

St. Catherine's, one of 66 parishes in the Diocese of Arlington, is an intensely private congregation, said its pastor, the Rev. Franklyn McAfee. "Everybody supports [the work of the church], but nobody stands out."

Or so it was until last week, when parishioner and FBI Special Agent Robert P. Hanssen was arrested on espionage charges. Suddenly, the church came under public scrutiny, and the names of its most famous members became widely known.

Supreme Court Justice Antonin Scalia and his wife attend regularly, as do Sen. Rick Santorum (R-Pa.) and FBI Director Louis J. Freeh and their families. So does Kate O'Beirne, the National Review's Washington editor.

Two Redskins quarterbacks, Gus Frerotte and Mark Rypien, were members at St. Catherine's during the years they played here. And House Minority Leader Richard A. Gephardt (D-Mo.) and wife Jane Byrnes Gephardt, who is Catholic, attended for many years.

About 30 percent of the members, including Scalia, O'Beirne and Santorum, live outside the geographic boundaries set by the diocese and had to make a written request to join. McAfee said that percentage is high compared with most parishes.

McAfee, 57, is aware of the potential power of his pulpit because of the influence on society some of his listeners have. The late Bishop John R. Keating knew it when he sent the priest there four years ago, telling him that it would be an awesome responsibility, McAfee recalled.

"It scares me sometimes," he said. "You rely on the Holy Spirit for guidance, but you really want to prepare [sermons well]. You don't want to misguide them or say something wrong."

Members say the presence of high-profile people does not change the character of the church. As one parishioner put it, "There's no VIP section here."

Generally, they add, people leave their professional labels at the door. McAfee said that until the Hanssen arrest, he was unaware that at least a dozen members of St. Catherine's are current or former FBI agents.

Do any of his congregants work for the CIA? "Maybe," he said. "If I ask somebody what they do and they don't tell me, I don't ask again."

During Masses last weekend, the pastor asked congregants to offer special prayers for the Hanssen family and for the FBI. After each service, one or more agents approached the priest to share their disappointment about last week's revelation.

St. Catherine's was founded in 1979, and its sanctuary was completed two years later. Membership grew from 1,272 in 1981 to 4,068 last year.

McAfee said he receives about 10 letters a month from potential members from outside the parish. They must explain why they want to join and tell their history of church involvement. "We don't want other parishes' malcontents," he said.

Scalia, Freeh and Santorum declined, through spokesmen, to be interviewed about St. Catherine's or the worship experience that brings them and their families back. But other members spoke freely of their appreciation of the church's colorful services and orthodox Catholic teachings.

They said they like to hear Bach and Mozart played by a classically trained organist and sung by an 18-member choir dressed in bright red robes. They like the 10:30 Latin Mass every Sunday, which the priests celebrate the old-fashioned way -- with their backs to the congregation, facing the cross. They like the monthly services where everyone sings Gregorian chants.

And they like priests whose attitude toward church teachings is to tell it like it is -- to assert that abortion is wrong, that divorce is a sin and that women can lead but not be priests.

"At St. Catherine's, they will talk about things that may not be popular, but they never avoid topics or saying what's wrong," said Roger Dolak, 70, who left what he considers a more liberal church near his home in Vienna to drive eight miles to St. Catherine's.

"God fills souls through orthodoxy, through the parish's steadfast commitment to the Gospel of Christ and to Catholic teachings," Dolak said. "And that's what's attracting people."

They also appreciate what McAfee calls "things to beautify," from the art inside -- including Byzantine-style icons of Jesus and Mary flanking the crucifix -- to exterior landscaping featuring 180 rosebushes planted around the building.

In interviews, several members testified to personal experiences of spiritual revival since joining.

Nancy Caro, 56, a native of Chile who lives in Great Falls, said that when she joined in 1985 she felt it was her obligation to attend every Sunday. But over the years, the church helped her draw closer to God. Now she is one of more than 100 people who go to Mass every day at noon -- not out of duty, she said, but because it's a joy.

"When people come into our parish, they really feel the presence of God when they go inside the church," she said. "I can't pinpoint exactly what it is, but something is different there."

Julian Heron, senior partner in a Washington law firm, said the first time he heard a sermon at St. Catherine's, in 1993, was the day God entered his life. He doesn't recall the words but remembers being conscious of his need for salvation. Heron soon converted from his Episcopal faith to Catholicism. Now, he says the rosary and studies Scripture regularly and attends Mass twice a week.

He sees Scalia and Freeh regularly but considers them just ordinary members. "St. Catherine's is very un-Washington," said Heron, 60. "People don't go there because they want to be seen with whoever. They go there strictly because the Lord is there. If you . . . didn't know what those people looked like, you'd never know they went there."

Such was the case on Ash Wednesday.

A crowd of about 450 people, predominantly white, Latino and Asian, filled the sanctuary for the evening service. A casually dressed mother and her crying baby sat next to a woman wearing a mink and a large diamond ring that sparkled in the pew. In front of them, a man wearing a black T-shirt and jeans crossed himself several times as he listened to McAfee's sermon on repentance.

With a diversity of people, the church offers various ways of meeting their spiritual needs, McAfee said. Every two months, St. Catherine's sponsors a healing Mass run by charismatic Catholics from outside the parish. Participants speak in tongues, offer prophetic messages and fall down on the floor -- "slain by the Spirit," in Pentecostal terms.

"People seem to really enjoy it, so I accommodate," said McAfee, whom parishioners describe as an intellectual, an introvert and a gifted homilist.

Last Sunday, he preached on the Eucharist, calling the sacrament "a conspiracy of blood to shatter our egos." Too many people, he said, take Communion without giving themselves fully to Jesus.

" 'I want to be me, not He,' they say. That whole stubborn attitude renders Communion useless," he said.

Several Catholic lay organizations meet at St. Catherine's, including the Knights of Columbus, Opus Dei and the Third Order of Dominicans. McAfee is confessor to two D.C. convents run by the Missionaries of Charity, Mother Teresa's order, and the parish is the regional base for the order and its lay missionaries.

Located in one of the wealthiest sections of Fairfax County, the parish is financially sound, with a 2000 budget of $830,000 and tithing pledges this year of more than $1 million.

Through a special campaign, the congregation raised $3 million for a new educational building to be completed by December on its 15-acre site. Eventually, the parish hopes to operate a private school out of the facility.

A half-mile from St. Catherine's, near Springvale Road and Georgetown Pike, a historical marker and boarded-up buildings and radar tower mark the location of one of 13 Nike missile sites the Army operated from 1954 to 1962 to protect Washington from Soviet air attacks.

McAfee noted the irony of the missile site's proximity in an interview this week, but otherwise he had little to say about the Hanssen case, explaining that he does not know Hanssen well. Hanssen, the third FBI agent ever charged with espionage, has been accused of selling secrets to the Soviets and Russians since 1985.

The revelation has been an embarrassment for some of St. Catherine's parishioners. But foremost, it's a sad moment for the church, they say.

Heron, the parishioner who found a spiritual home on his first visit to the church, began crying when asked what effect Hanssen's arrest has had on the parish. He said that he didn't know Hanssen but that hearing about the charges against him was an emotional blow, almost like the death of a family member.

"It's a tragedy for all of us," he said.

Ian Didion, 9, lights a candle during Mass at St. Catherine of Siena Catholic Church in Great Falls.St. Catherine of Siena Catholic Church in Great Falls opened 20 years ago and has grown to more than 4,000 members. About 30 percent come from outside its parish boundaries.St. Catherine of Siena is expanding on its 15-acre site with an education building, due to be finished by December.ROBERT P. HANSSENJANE BYRNES GEPHARDTANTONIN SCALIAGUS FREROTTELOUIS J. FREEHDeacon Joseph Benin, right, and the Rev. Franklyn McAfee put ashes on the foreheads of parishioners.The Rev. Franklyn McAfee puts ashes on a worshiper's forehead at Ash Wednesday Mass at St. Catherine's.