The Archdiocese of Philadelphia's decision to close 49 ailing schools may produce quick financial benefits, but its long-term impact on the faith of young Catholics might not be so positive.

Children who attend Catholic elementary schools are likelier to make first Holy Communions and be confirmed, according to studies.

Those who graduate from Catholic high schools are likelier to believe church teachings, marry and raise their children in the faith, and play leadership roles in their parishes.

"There really is a guiding effect" of schools on Catholic identity, according to Mark Gray, director of Catholic polling at Georgetown University's Center for Applied Research in the Apostolate.

The impact of secondary schools on long-term faith is even greater.

"Attending Catholic high school for at least three years significantly reduces the likelihood that one disaffiliates from Catholicism" in adulthood, a study by the center found.

"It's a total immersion," said Karen Ristau, president of the National Catholic Educational Association. Catholic schools reinforce students' faith and worldview "all day, every day."

But with just 9 percent of high-school-age Catholics attending Catholic schools, it's an immersion for a relative few, said Bob McCarty, executive director of the National Federation for Catholic Youth Ministry.

The Catholic school population is in such steep decline, McCarty warned last week, that "we have to completely rethink how we do discipleship."

Catholic dioceses in the United States have closed 1,755 schools since 2000, according to the National Catholic Educational Association, and the number of pupils has dropped by 600,000.

These economically driven closings come at a time when many American Catholics are drifting away from traditional practices of their faith.

The Philadelphia Archdiocese reported that only 24 percent of its registered population now attends Mass on any given weekend. Weekly Mass attendance declined 14 percent across the archdiocese between 2006 and 2010, and reception of Holy Communion has dropped 11 percent.

Nationally, two out of three Catholics in their 20s and 30s say they rarely attend Mass outside Christmas and Easter, according to a study by the Georgetown University center. And this cohort of "Christmas and Easter" Catholics is far less likely than previous generations to rate baptism, marriage, Eucharist, and confession as "very meaningful" in their lives.

Just 44 percent of that group regard reception of Holy Communion - the heart of Catholic observance - as important. Half say they don't think of themselves as particularly religious.

Such views are not unique to Roman Catholics.

A 2007 study by the Pew Forum on Religion and Public Life found that today's young people "are much less likely [than their elders] to affiliate with any religious tradition or to identify themselves as part of a Christian denomination."

One in four Americans between 18 and 30 describe their religion as "atheist," "agnostic," or "nothing in particular," according to Pew.

But in their 2005 report, "Catholic Schooling and Disaffiliation from Catholicism," Gray and co-author Paul Perl found that Catholics who graduate from Catholic high school were half as likely to convert to another faith as those who did not attend, and 44 percent less likely to abandon religious affiliation.

Gray and Perl surmised that Catholic high schools reinforce religious identity by creating enduring social bonds.

"Attending Catholic high school occupies a large portion of day-to-day life and seems likely to enmesh one in an array of close, dense social ties, creating an experience of living in the midst of a Catholic community," they wrote.

In McCarty's view, it is imperative that dioceses, parishes, and parents create new, enmeshing Catholic communities - similar to what schools did - if they want to hold on to their young.

To that end, he argued, parishes must make parish life engaging for whole families, and parents must take a more proactive role in transmitting their faith to their children.

For too long, he said, Catholic parents abandoned that role to schools. "Their attitude was, 'You make my kid believe in God. You make my kid Catholic,' " McCarty said. "But that ship has sailed."