ROME - 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, including the prospect of schisms in intercontinental churches and political frictions within and between countries.

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 FranCOis Bordarier of Lille, in northern France, "but that there are any at all."