Stanley Hauerwas, author of the forthcoming book “The Character of Virtue: Letters to a Godson,” is the Gilbert T. Rowe emeritus professor at Duke Divinity School.

In the 1950s, Pleasant Grove, Tex. (now southeast Dallas), where I grew up, was a white working-class town where Catholics did not exist. For me, the religious "others" were Southern Baptists, whose distinctiveness was summed up in their refusal to dance. Our world was a Protestant world, and I was a Protestant, because what else would I be? For years, this sentiment sufficed. Then I began to learn about Catholicism.

I have been thinking about Christianity for my whole life. I've spent my career as a Protestant theologian at the University of Notre Dame and Duke Divinity School. I have written many books on theology and ethics. But I still don't know how to think about the 500th anniversary of the Protestant Reformation this coming week. Divorces (some Christian traditions still call Luther's revolt "the great schism") are not to be celebrated; they leave a scar. The problem is that I, like many Protestants, don't see the gulf between us and our Catholic brothers and sisters as particularly pronounced. The separation I once saw as default now makes less sense to me. Why am I not a Catholic?

My first inkling of this intellectual problem began as a philosophy major (actually, the philosophy major) at Southwestern University in Georgetown, Tex., where I was lucky enough to have a teacher to take me through Frederick Copleston's multi-volume "History of Philosophy." Copleston was a Jesuit, though at the time I had no idea what that meant. I began to grasp the distinctness and fullness of the Catholic tradition during my graduate work at Yale's Divinity School. I attended with no intention to be ordained; I simply wanted to know if what Christians believed could be considered true. Even then, something about Catholicism seemed remote: The Second Vatican Council was underway, which meant we students read Catholic theologians — Rahner, Haring, de Lubac, Congar — on how theology should be done in modernity. But we barely took note of their faith. We also read Martin Luther and John Calvin, but we considered them late Medieval thinkers who had more in common with Thomas Aquinas than our divnity school mentors.

In short, the Reformation seemed to us to be "back there," and I felt no need to defend Protestantism because it seldom occurred to me that being a Protestant was all that important or interesting. The antagonism of the past simply seemed no longer relevant. It was the '60s; we were attracted to theology as part of a general attempt to make the world better. Protestant-Catholic sectarianism didn't feel current.

In 1974, I interviewed for my job teaching theology at Notre Dame. Things were going well until a professor on the hiring committee asked what I wanted to teach graduate students. I said I would like to teach a seminar on Aristotle and Aquinas. The response was immediate: "Why would you, a Protestant, want to teach a course on a Catholic thinker?" Christianity did not begin in the 15th century, I replied. I argued that Aquinas was not a possession of Roman Catholics but a resource for all Christians, whether Protestant or Catholic.

It was a small moment, but in that exchange, I began to understand that we were in a new day: Five hundred years after its inception, we are witnessing the end of the Reformation. The very name "Protestant" suggests a protest movement aimed at the reform of a church that now bears the name of Roman Catholicism. But the reality is that the Reformation worked. Most of the reforms Protestants wanted Catholics to make have been made. (Indulgences are no longer sold, for instance.) A few Protestant denominations might still be anti-Catholic (consider evangelical pastor Robert Jeffress's claim, recently publicized, that Catholicism has Satanic origins ), but the original idea that Catholics adhere to a legalistic perversion of Christianity that does not admit the free grace of God is seldom seen, these days, as the Protestant difference from Catholicism. Over time, historians have helped us see that there was no one thing the Reformation was about, but that if there was a single characteristic at its heart, it was the recovery of the centrality of Christ for making sense of why Christians are not at home in this world. That emphasis turned out to be the overriding insight that shaped the work of Vatican II, meaning Catholics have overcome the major thrust of the Reformation.

That the Reformation has been a success, however, has put Protestantism in a crisis. Winning is dangerous — what do you do next? Do you return to Mother Church? It seems not: Instead, Protestantism has become an end in itself, even though it's hard to explain from a Protestant point of view why it should exist. The result is denominationalism in which each Protestant church tries to be just different enough from other Protestant churches to attract an increasingly diminishing market share. It's a dismaying circumstance.

But I am still a Protestant, even though I'm not sure I know what I am saying when I say I am a Protestant. I can think of my life only as a living ecumenical movement — I was raised Methodist, taught Lutherans (Augustana College), was overwhelmed by the Catholic world, was deeply influenced by the Mennonites and finally returned to the Methodists at Duke. All of which, of course, means I have ended up worshiping at the Episcopal Church of the Holy Family in Chapel Hill, N.C. That I am a theologian more defined by where I went to graduate school than by any ecclesial tradition mirrors changes in the Protestant world — in particular, that the gulfs between the denominations seem only to feel smaller and smaller. And so does the gulf between Catholicism and Protestantism.

Under the influence of the great Protestant theologian Karl Barth, an emphasis on the centrality of Christ has been the hallmark of my work in ethics. Yet, perhaps tellingly, a number of my Protestant graduate students have become Roman Catholics over the years. (So many crossed the Tiber that my colleagues joked I was an agent for Opus Dei.) They convert because Catholicism is an intellectually rich theological tradition better able to negotiate the acids of our culture. They also take seriously that Roman Catholicism represents a commitment to Christian unity, not only toward non-Catholic Christians but between the poor and those who are not poor.

I have watched these students join the Catholic Church over the years. They are not wrong. And yet, I remain a Protestant. It is hard for me to explain why that is. No doubt there are many reasons, not the least being I am married to a woman who is ordained. But I also remain a Protestant because I have the conviction that the ongoing change that the church needs means some of us must be Protestant to keep Catholics honest about their claim to the title of the one true Catholic Church. The Reformation may be coming to an end, but reform in the church is never-ending, requiring some to stand outside looking in.

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