Twelve years ago, when Pope John Paul II lit up an arena packed with cheering throngs of teens and 20-somethings in downtown St. Louis, I was working a few blocks away as the youngest member of the St. Louis Post-Dispatch editorial board. My colleagues, most of whom were Baby Boomers and self-professed secular humanists, were stumped by the Pope’s popularity. Why, they asked me, were young Catholics stampeding to see this frail, palsied pope who sermonized about sexual purity and self-sacrifice? Isn’t youth the time to rebel against religious authority? What’s with young people today, anyway?

Many Baby Boomer Catholics had been asking similar questions since 1993, when hundreds of thousands of American teens and young adults turned out to cheer John Paul at World Youth Day in Denver. They puzzled over the seminarians who labeled themselves future “JP2 priests,” the high school and college students who marched on the National Mall each January sporting T-shirts emblazoned with John Paul’s pro-life quotes, the young singles who clustered in parishes and pubs to discuss his theology of the body and the young couples who boasted growing families in which it seemed that at least one boy almost always bore the name of the only pope his parents had ever known, John Paul.

Their questions intrigued me and I had my hunches about the answers, but I wanted to get the story straight from young Catholics themselves. So with the help of a Phillips Journalism Fellowship, I took a year off my newspaper job and traveled America to interview some 500 young Catholics and other Christians about their spiritual journeys and religious commitments. The result was my book The New Faithful: Why Young Adults Are Embracing Christian Orthodoxy (Loyola, 2002), which tells the story of young Catholics and evangelicals swimming against our culture’s secularizing tide.

Given what I had witnessed when John Paul visited St. Louis in 1999, I was not surprised to discover that his influence played a major role in many of the conversion stories I heard. His name surfaced again and again, not only among Catholics but also among Protestants. They saw him as a modern-day icon of heroic Christian virtue, one of the few voices in the world willing to speak boldly to them about what it takes to achieve happiness, holiness and freedom in Christ.

Since publishing The New Faithful, I have continued to keep in touch with many of these interviewees and track the ways that the young Catholics among them are living their faith. The maturation of these new faithful — members of the “JP2 Generation,” as it has become known — has not dimmed the Pope’s influence on their lives. But that influence has deepened and changed in the six years since his death, when 4 million pilgrims, the vast majority of them young people, descended on Rome to bid farewell to their beloved Holy Father.

There are the obvious signs of John Paul’s continuing influence on this generation, the oldest edge of which is moving into leadership roles in the Church. For starters, there are the schools: More than a dozen Catholic high schools in the U.S. now bear his name, not to mention several grade schools and Newman centers, and even one university. His model of cheerfully engaging, bracingly orthodox youth ministry slowly is becoming the norm rather than the exception in many schools, parishes and dioceses, as young Catholics assume the task of passing the faith to the next generation.

This model also is spreading to college campuses — and not only Catholic ones. At secular schools such as the University of Nebraska-Lincoln and North Dakota State University, hundreds of students now participate in Corpus Christi processions to publicly show their reverence for the Blessed Sacrament in a blend of traditional piety and cultural confidence that epitomizes John Paul’s New Evangelization. Inspired by his bold proclamation of Catholic sexual ethics, college students across the Ivy League and beyond have begun forming campus social clubs to promote chastity among their peers in union with the Love and Fidelity Network.

Beyond campus, many young Catholics are taking the convictions they learned from John Paul — about the injustice of abortion, the sanctity of marriage and the necessity of defending life from the cradle to the grave — into the public square and the voting booth. Their passionate commitments to building a culture of life appear to be influencing even their non-Catholic peers. A recent Gallup poll found a significant rise in the percentage of young Americans who believe that abortion should be illegal in all circumstances, from about one in seven in the early 1990s to one in four today. Eighteen-to-29-year-olds are now tied with seniors as the group most likely to favor the outlawing of abortion.

In the realm of priestly and religious vocations, there are signs of youthful renewal. The National Religious Vocation Conference reported in 2008 that 62 of its member religious communities had seen a rise in inquiries from prospective members in the past year and the average Catholic religious community saw a 30% jump in the number of new members entering formation that same year. A 2009 study by Georgetown University’s Center for Applied Research in the Apostolate found that the communities attracting young Catholics today are those that emphasize the particulars of religious life that John Paul did: a focus on prayer, community, fidelity to Church teaching and the wearing of a distinctive religious habit.

John Paul’s greatest legacy among young Catholics may be his eloquent defense of married life and love. The trickle of theology of the body study groups has become a flood, and the vigorous recent debate over the meaning of John Paul’s teachings on human sexuality only underscores their importance to young Catholics who see them as a lifeline in today’s sexually chaotic culture. Many of the young Catholics who praised those teachings to me a decade ago now are forming their own marriages and families and centering them on the principles John Paul imparted to them. They are rejecting artificial contraception, putting prayer at the heart of family life and finding creative ways — including home schooling — to ensure that their children inherit their Catholic faith. They face struggles, disappointments and temptations. Many feel shaken by the new revelations of clergy sex abuse and cover-ups that have come to light in the past year. But their faith has matured into an organic part of their lives, something less emotional and personality-driven and more suited to weather tough times.

Not all is rosy with the JP2 Generation. Mass attendance among young adults who fall outside this “new faithful” cohort, and among American Catholics in general, is depressingly low. Youth support for same-sex “marriage” is at an all-time high. And many young Catholics feel little connection to the Church, despite fond memories of the Pope who led it for 26 years.

Still, the soon-to-be Blessed John Paul planted seeds of faith, hope and love that have borne lasting fruit in this generation, fruit that will continue to ripen in the decades to come. As one young woman told a reporter at his funeral, “The Pope loved us enough to tell us the truth.” That truth is one that JP2 Catholics now want to proclaim to the world.