ROME, Oct. 12--Like many Italians in decades and childhoods past, Giampaolo Servadio used to go to Roman Catholic Mass every week. He even served as an altar boy.
But last Sunday morning, as church bells tolled around this city of storied cathedrals, he followed a different ritual: he went running. It struck him as a more relevant use of time.
"The church seems really out of step," said Mr. Servadio, 39, mentioning issues like birth control and questioning the very utility of prayer. "I don't see how something like a confession and a few repetitions of the 'Hail Mary' are going to solve any problems."
He wondered if he should call himself Catholic: "When you realize that for 20 years you don't do this--you don't even go to church--what kind of Catholic are you?"
A fairly typical one, at least in Italy and much of Europe, where the ties of Christianity no longer bind the way they once did--and often seem not to bind at all.
This week Pope John Paul II is to celebrate his 25th anniversary as the head of the Roman Catholic Church, which is both Europe's and Christianity's largest denomination.
It has been a quarter century of enormous changes, and few have been more significant, for his church and mainstream Protestant denominations, than the withering of the Christian faith in Europe and the shift in its center of gravity to the Southern Hemisphere.
Christianity has boomed in the developing world, competing successfully with Islam, deepening its influence and possibly finding its future there. But Europe already seems more and more like a series of tourist-trod monuments to Christianity's past. Hardly a month goes by when the pope does not publicly bemoan that fact, beseeching Europeans to rediscover the faith.
Their estrangement has deep implications. The secularization of Europe, according to some political analysts, is one of the forces pushing it apart from the United States, where religion plays a potent role in politics and society, shaping many Americans' views of the world.
Americans are widely regarded as more comfortable with notions of good and evil, right and wrong, than Europeans, who often see such views as reckless.
In France, which is predominantly Catholic but emphatically secular, about one in 20 people attends a religious service every week, compared with about one in three in the United States.
"What's interesting isn't that there are fewer people in church," said the Rev. Jean François Bordarier of Lille, in northern France, "but that there are any at all."
While France is an extreme case, its drift from Christian institutions and disparity with the United States hold true throughout much of Europe, where faithful attendance at Christian services, be they Catholic, Protestant or Orthodox, is the province of a small minority of people.
They show up to mark crucial milestones in their and their loved ones' lives. But they pay minimal heed, between those visits, to their churches' exhortations and admonitions.
The tension between contemporary attitudes and traditional church teachings has forced an emergency meeting this week of the leaders of the worldwide Anglican Communion.
They are expected to debate the acceptability of openly gay bishops in their church. Representatives from congregations in the developing world have threatened to break the church in two if their Western peers head in a permissive direction.
The preamble of a new, unfinished constitution for the European Union omits any mention of Christianity or even God among the cultural forces that shaped Europe, although the pope and other Christian leaders raised vehement objections. …
By some estimates, more than 25 million people in England identify the Church of England as their denomination. Only 1.2 million actually go to one of the church's services every week.
Other Protestant denominations are in the same shape.
"In Western Europe, we are hanging on by our fingernails," wrote the Rev. David Cornick, the general secretary of the United Reformed Church in Britain, in the June-July edition of Inside Out, a religious journal. "The fact is that Europe is no longer Christian."
That is something of an overstatement. Despite a recent influx of Muslim immigrants and the rise of mosques in countries like Britain, France and Germany, an overwhelming majority of Europeans who profess religious devotion consider themselves Christian. But for most, Christianity has evolved into an amorphous spiritual inclination rather than an exacting creed.
Stéphanie Vercamer, a 31-year-old florist in Lille, wears a gold cross around her neck and said it saved her from injury in a car crash several years ago. "There is a God," Ms. Vercamer said. "I wouldn't be here today if there wasn't."
At the Saint Sacrement church in Lille, attendance at Mass often drops below 50 but rose above 125 on a recent weekend. The Rev. Émile Reyns, a priest there, gladly reported that he had recently done prenuptial counseling for six couples: proof, he said, that young adults still wanted Catholic weddings.
But he sadly conceded that all the couples had been living together for a while.
"In terms of religion, Europe is very complicated," said the Rev. Andrew M. Greeley, the author of "Religion in Europe at the End of the Second Millennium," which was published this year.
Sizable majorities of people in most European countries believe in God, and sizable majorities believe as well that some kind of religious service is important when a person dies, according to the European Values Study, a sweeping survey conducted in 1999 and 2000 and published this summer.
But they are less familiar with, or tethered to, the specific rituals and roots of Christian worship. "If you ask the average European the basic credo or statements of the Christian church, most of them don't know," said Grace Davie, a sociologist at the University of Exeter and the author of several books about religious trends in Britain and Europe.
That assessment is supported by the caretakers of the faith themselves.
Last month Cardinal Dionigi Tettamanzi, the archbishop of Milan, said at a news conference, "The parishes tell me that there are children who don't know how to make the sign of the cross."
"At the elementary schools, they don't know who Jesus is," added the cardinal, who is widely considered to be a strong candidate for the papacy.
According to the European Values Study, only about 21 percent of all Europeans said religion was "very important" to them. Although the methodology was not precisely comparable, a Gallup Poll this year showed that 58 percent of Americans defined religion that way.
Even in Italy, where 33 percent of respondents described religion as "very important," the percentage of Italians who go to church every week is as low as 15 and no higher than 33, according to various polls.
Most Italians seem not to listen to the Vatican, even though about 85 percent identify themselves as Roman Catholic and the pope resides smack in the middle of their country.
John Paul has exhorted them to be fruitful and multiply, forbidding artificial birth control. But Italians have had one of the world's lowest fertility rates for a quarter century now.
Public schools throughout Western Europe have removed crosses from walls. Many congregations have been forced to close or combine operations, to make do with part-time ministers or to import pastors from the developing world.
On this continent, ministry has lost much of its luster.
"In Western Europe," said Archbishop Giuseppe Pittau, the secretary of the Vatican congregation in charge of seminaries, "it's been almost a tragedy. A diocese that once had 10 priests ordained every year might have two, or one, or less."
The desperation is evident. In September, when a group of Catholics in a rural town near Rome heard that the local monastery would be closed and the monk would be sent away, they kept him there for several days by bricking up and barricading the entrances.
There are many suggested reasons for Europe's drift, which happened gradually, over decades, as the continent grew wealthier and better educated.
Some experts say that in Europe, suspicion of major denominations may run higher because religious leaders directly wielded political power in the past. Others say the unchallenged supremacy of state-blessed faiths in Europe--like the Lutherans in Scandinavia and Anglicans in Britain--perhaps turned out to be a curse.
"Monopolies damage religion," said Massimo Introvigne, the director of the Center for Studies on New Religions in Turin and a proponent of the relatively new theory of religious economy. "In a free market, people get more interested in the product. It is true for religion just as it is true for cars."
It also has reverberations well beyond the pews.
"I've been struck by the way in which religion now serves to underpin the divergence between Europe and the United States, and where I particularly saw that over the last year or two was in attitudes about the Middle East," said Philip Jenkins. Dr. Jenkins is a British scholar who teaches history and religious studies in the United States and wrote "The Next Christendom" (2002), about changing patterns of Christian worship around the world.
"Americans still take biblical and religious arguments very seriously, and therefore give a credence to the Zionist project that Europeans don't," Dr. Jenkins said.
He said that for many Americans, the frequency with which President Bush invoked morality and religion in talking about the fight against terrorism was neither striking nor discomfiting. "But in Europe," he added, "they think he must be a religious nut."
Some sociologists say new data suggest a possible reawakening of Christian interest in people under 30, and Christian movements throughout Europe are reaching out aggressively to them.
The Emmanuel Community in France has wooed hundreds to gatherings like one in Paris on a recent Saturday night, where scores of well-dressed professionals nibbled quiche and sipped wine in a courtyard under the moonlight.
Then, around 10 p.m., they hurried across the street to a centuries-old cathedral where they titled their heads backward, lifted their palms heavenward and rocked back and forth, in thrall to a religious ardor that most of Europe has lost.