The outpouring of grief for Pope John Paul II reflects the extraordinary admiration and love Roman Catholics feel for their holy father. But, as the pope noted, loving a father is not the same as obeying him.

On the key issue of artificial birth control, a large majority of Catholics in the United States, Europe and many developing countries have broken with the pontiff and the church's long-standing ban on contraception.

There is perhaps no other central teaching that so many Catholics have rejected in belief and practice. It is an issue the next pope surely will have to confront -- most urgently on the narrow question of allowing condoms to prevent the spread of HIV-AIDS.

More than three-quarters of Catholics in the United States say the church should allow the use of artificial birth control, according to a recent Gallup Poll. And millions ignore the ban every day.

One of them is Linda S. Pieczynski, a national spokeswoman for Call to Action, the nation's largest Catholic reform organization. The mother of three girls says she has always used artificial birth control. "I've read everything I could, and I don't really believe in my conscience that I'm sinning," she says.

She's wrong, according to traditionalists such as the Rev. Lawrence P. Adamczyk, associate pastor at the Cathedral of Mary Our Queen in Baltimore. Catholic couples who choose artificial birth control are committing a grave sin, he says, and when it is committed with full knowledge and full consent, it is a mortal sin.

"People who die in a state of mortal sin suffer eternal separation from God, which we would call hell," he said.

But surveys and birthrate statistics show that many Catholics reject that view. Italy, which is 97 percent Catholic and the seat of the Vatican, has the lowest birthrate in Europe, and that rate has declined since John Paul was elevated in 1978.

Even in Latin America, where the church is far more conservative than in the United States and Europe, there is evidence that birth control is widely accepted. Surveys commissioned by Catholics for a Free Choice have found that 87 percent of Catholics in Colombia believe that a person can use artificial contraception and still be a "good Catholic." More than 80 percent in Mexico and Bolivia agreed. In Brazil, 70 percent of Catholic women of child-bearing age said they had used modern contraception.

But even for Catholic birth-control advocates, this is old news. "The issue is long-since solved, and nobody talks about it," said the Rev. Charles E. Curran, a Catholic priest and professor of human values at Southern Methodist University.

Modern Catholic teaching on birth control has its roots in a 1951 encyclical by Pope Pius XII, who condemned artificial contraceptives as a violation of natural and divine law.

In 1965, Pope John XXIII appointed a commission to revisit the issue. In a report to John's successor, Pope Paul VI, the panel of theologians, priests, bishops, cardinals and laypeople concluded that artificial birth control was not intrinsically evil and proposed that Catholics be allowed to decide the issue for themselves.

But Paul rejected the proposal. In his 1968 encyclical Humanae vitae ("On Human Life" ), he reasserted the Church's "constant doctrine" that "every marriage act must remain open to the transmission of human life."

Objections to Humanae vitae from church dissenters were immediate. The day after it appeared, a group of 80 American theologians (hundreds more later signed on) argued that the encyclical's reasoning was faulty. They said it considered only the sex act, to the exclusion of the relationships between the people involved.

Among the dissenters was SMU's Curran, who argued that Humanae vitae was a "moral teaching" that had not been declared infallible. Under church doctrine, when there is "sufficient reason," and after searching their consciences, people can depart from official teaching and still be loyal Catholics, he said.

Curran was condemned by the church for his outspokenness and eventually lost his teaching job at Catholic University.

John Paul, who referred to sexual expression as "the language of love," reinforced that doctrine and stated that all forms of artificial contraception were intrinsically evil because they interfered with the transmission of life and the total and "reciprocal self-giving" required of married couples. (Sex outside of marriage, of course, remains forbidden.)

Today, Curran argues, the official ban on contraception has more to do with maintaining church authority than affirming life. "It has nothing to do with birth control. It's 'If we admit we're wrong here, we would have to admit we might be wrong on other issues.' They're terribly worried about the slippery slope."

So the ban has held firm. The church says "barrier" contraceptives such as condoms are wrong because they foreclose the sex act to "the transmission of life." Similarly, some birth-control pills prevent ovulation.

Worse, according to doctrine, some could prevent the implantation of a fertilized egg -- tantamount to causing the death of a genetically unique human being.

Tubal ligation and vasectomies are regarded as "mutilations" that likewise violate natural and divine law.

Some priests who matured under John Paul are also more aggressive about dealing with a matter they see as central to Catholic teaching about God as the author of life, and about men and women -- and their sexuality -- as part of God's plan.

"When Mary and Jesus gave themselves over to the will of the Father, they gave themselves completely. Nothing was held back from the one they loved," said the Rev. Leo Patalinghug of St. John Roman Catholic Church in Westminster, Md.

Unlike some colleagues who avoid the subject, Patalinghug says he has become known as "the sex priest" because he deals with contraception directly when he counsels young people and couples preparing for marriage. Patalinghug tells couples that the notion that they are protecting themselves with contraceptives will eventually "cheapen" the act.

"When you use a condom or the pill, what makes that act different from going to a prostitute?" he says. "The reason is you are 'protecting yourself.' From what? The one you love? Sex should be fearless, and the world is making it something to be feared."

Patalinghug instead tells couples about "natural family planning," the only church-approved method of contraception. It's a series of techniques for monitoring the woman's ovulation cycle by tracking body temperature and the consistency of cervical mucus.

During the seven- or eight-day period each month when the woman is fertile, the couple simply abstains from intercourse. Patalinghug said the technique is "based on pure science" and is "99.999 percent effective."

Dr. Paul D. Blumenthal, director of contraceptive research at Johns Hopkins Bayview Medical Center, agreed that the natural technique can be effective, but not quite that good. Couples who manage it perfectly can have failure rates as low as 2 percent to 9 percent, he said. "However, most people have a tough time following all the rules, and many have lapses of discipline." With "typical" use, failure rates are more like 15 percent to 25 percent, he said.

By comparison, failure rates for women on the pill are 1 percent to 3 percent with perfect use, and 5 percent with typical use, according to the Center for Young Women's Health at Children's Hospital in Boston.

Some of the strongest pressure on the church hierarchy for change comes from Catholics who advocate condoms as a method to prevent the transmission of HIV-AIDS, which is rampant in some parts of Africa.

"Sometimes you have to choose the greater good to prevent an evil," Pieczynski said. "The deaths of these people are wrong when we have a way to prevent them."

But Adamczyk takes a different view of an AIDS carrier who wants to have sex: It's selfish. "What that action is saying is that 'I want to have my pleasure, but I don't want to use it in the way God intended. I don't want to hurt you, but I still want my pleasure,'" he said.

No matter what the polls show, the conservatives who rose to power in the church under John Paul are unlikely to give way on contraception.

"We do believe in a shared wisdom," Patalinghug said. "But we also know, in the church, we're not a democracy. And the reason is that a democracy is based on social principles, and we have to base our teachings on theology rather than sociology."