She was sitting in the living room of her Silver Spring home, folding a stack of diapers as she talked about the Catholic faith and the issues of most concern to her. In the next room, a baby of two months -- her third child -- was cooing softly as it awakened.

"The main issue," said the woman, "is birth control."

After the birth of the baby, the woman and her husband, members of St. Bernadette's parish in Silver Spring, decided to use contraceptives so they would not have any more children. The decision was based partly on family finances, partly on the mother's health and age. But because of Roman Catholic Church opposes any form of artificial contraception, it was a difficult moral decision.

"I would love to have 10 kids," said the woman, who asked to remain unidentified, "if I had a big enough house, could pay for all the groceries, for their clothes, for their Catholic schools. But we just can't do that. Some of these priests live in their own little world, and they just don't realize how much it costs to have children and raise them until they're 18 or 20.

The one person with the authority to change the Roman Catholic position on this fundamental issue is Pope John Paul II, who will visit Washington Oct. 6 and 7. So far in his term, the new pontiff has supported Pope Paul VI's encyclical, Humane Vitae, which set forth the church's policy against artificial birth control.

In his visit here, church leaders say, the pope will stress the sancity of marriage, the importance of the family and the value of human life. They do not expect him to make any specific statements on birth control, which is perhaps the most fundamental, and certainly the most controversial, issue faced by the Catholic Church in America.

In the 1960s and early 1970s, according to studies conducted by Father Andrew Greeley, the Catholic writer, the church's birth control teaching was the primary cause of Catholics abandoning the faith. In the last few years, several church theologians say, the situation has taken another turn. Now, more and more Catholics are remaining in the church but disregarding its dictums on the subject of birth control.

"Statistics seem to indicate a lot of people, Catholic people, are using artificial birth control and somehow they've reconciled it with their consciences," said Father John Connery, a theologian at Loyola University of Chicago. It is an unhealthy trend, added Father Charles Curran of Catholic University, because "it can hurt the credibility of the church as a teacher."

In any case, many church leaders believe birth control will loom ever larger as a religious issue in the future years of Pope John Paul II's term, and nowhere will the discussion be more intense than in the cities of America that the pope will soon visit.

In a family-oriented parish such as St. Bernadette's where it is not unusual to see parents walk up to the Communion alter carrying one child in their arms while several other youngsters trail behind, the pastor has made the church's policy clear -- artificial birth control is objectively evil.

Those practicing artificial birth control are reminded that it is considered a "serious sin" which prevents them from receiving Holy Communion, the sacrament through which they are united with Christ on earth.

The pastor at St. Bernadette's, Monsignor David E. Foley, said he is aware that many of his parishioners "are struggling with this particular problem in their lives." A priest dealing with the issue, he said, must "be sympathetic and understanding . . . and help them through."

The answer at St. Bernadette's is to encourage couples to attend seminars on the Billings ovulation method of birth control, which church officials have sanctioned as a "natural form" of family planning because it is based on training women to know when they are in their fertile period and most likely to conceive a child.

"We are always running announcements in the Sunday bulletins to let our parishioners know when there is a seminar on the Billings method at Holy Cross Hospital or at Georgetown Hospital," said Foley. "The church, you see, is not against responsible family planning."

The emphasis on family life is evident in several ways at St. Bernadette's. About 50 parishioners are active in the anti-abortion movement, according to Tim Murphy, whose wife, Sally, chairs the parish anti-abortion committee. A recent "pro-life education night" drew about 80 people and the meeting went on until about midnight, Murphy said.

In addition, the parish's 500-member Sodality is active in Birthright, an organization geared toward helping women through "stressful pregnancies."

Still, for many families at St. Bernadette's, the issue of birth control is a constant source of concern. Parents in their thirties and forties, with families of two and three children, talk of their decision to use contraception with a sense of guilt that is hard for some non-Catholics to appreciate.

"I'm not completely convinced I'm doing the right thing, but I don't see where I have any choice," said one young mother of three from St. Bernadette's. "My husband absolutely believes in birth control, so what do you do? If I didn't use it, my marriage, I'm sure, would break up. And then, the church is also against marriages breaking up . . . "

Her husband put it this way: "I respect what the church says. But you also have to look at it from the point of view of having to support these kids. I don't think the church has the right to tell people to disregard this."

For Catholic parents who adhere to the teachings of the church, the Billings method is the only acceptable means of family planning. Even a couple such as Sarah and Jim Willging, who have six children and believe all artificial birth control is "against God's natural law," have considered using this method.

"We've been praying a little harder for guidance," said Sarah Willging. "With the twins and four other children 11 and under, it takes 24 hours just to do the nitty-gritty things like laundry and dishes. It takes a lot of me to get through the day."

"I can't say it doesn't scare me, the thought of having another baby. I say to myself, 'Gosh, will I be able to deal with it?' But I know it wouldn't be impossible. I know the Lord would give me the capability to love another child and the patience to deal with this."

For unmarried Catholics who practice birth control, the issue strikes even deeper, given the church's stand against premarital sex. One 22-year-old woman who recently returned to St. Bernadette's parish said that she deliberately stayed away from mass for three years because she was using birth control pills.

"I didn't feel I was doing what a person who belonged at church would be doing," she said. She added, however, that it was her own fault, not the church's, that she felt she could not attend mass.

"What I was feeling inside of me, well, it's not so simple as comparing it to the feeling of disobeying your mother. You see, deep down inside, I really believe certain things, like it's good to wait until marriage. I believe the act of sex should be sanctioned by marriage."

After three years, with the help of a priest, the woman said she began to reconcile her feelings about birth control with her Catholic faith.

"Part of it is just forming your own conscience," she said. "Now I just feel it's okay . . . I know I won't be jumping from one person to another. I don't think I'm going to hell for sex."

Msgr. Foley said he believes that "young people are not loved as they were in past generations and often feel alone." But he encourages young unmarried couples who are living together to break up immediately.

His reasoning: "If they're just lonely and need someone who cares, then we ask them to ask themselves, 'What does Christ say to me? What is the need I have for Chirst? Isn't that greater than my need for human companionship?'"