Excerpted from "Why I Am a Catholic" by permission of Houghton Mifflin Company.

This book is an unintended sequel to my Papal Sin (2000)--unintended because I thought that book treated a narrowly defined and self-enclosed topic, the papacy's dishonesty in its recent (anti-modern) era. ...

I did not anticipate, though I should have, that people would write me, in large numbers, sincerely asking what would be a valid defense of the papacy. How does one remain a Catholic while criticizing some of the church's authority figures? I have never received mail of this kind or quantity in my forty years of writing. Most people who wrote me in the past were upset or outraged at something I had published. Those who agree with you just nod, most often, in silent agreement and move on; they have no need to vent their feeling.

But in this case the overwhelming number--over ninety percent--of letters and calls and comments began or ended with a thank-you for expressing what the correspondents felt, for letting them know they are not alone or that their own views could be expressed. These correspondents included priests and nuns who welcomed the call for candor in the church. That made all the more compelling some requests that I expand my book's closing comments on what positive things the church does or can do. What, they asked explicitly or implicitly, are the grounds of my own hope? Why am I still a Catholic? This I took as their way of exploring why they remain in the church. They were asking to compare notes.

Naturally, there were negative reactions to the book--in some cases, extremely negative. These differed from the first and larger group of responses in many ways. For one thing, the writers expressing gratitude proved by their questions that they had read the book. But some of the angriest letters I got admitted that the writer had not read my book, only some review of it in a conservative publication on the Internet or elsewhere. (I had not realized there are so many right-wing Catholic organs, ones I had never heard of, nor had Catholic friends I asked about them.)

The first group asked how I stayed in the church. The second asked why I did not leave. Those writing out of gratitude assumed that I shared their (sometimes baffled) love of the church. The accusatory group flatly informed me that I hate the church, that I stay in it only to harm it, that I should get out before I do it irreparable damage. (Despite their belief in the church's divine mandate, these people express a great anxiety over its fragility--another attitude that makes shoring up the church with any material, even lies, seem justified.) So this group, too, asked, why I am still a Catholic, but in a different tone of voice. They meant, "Why are you keeping up this pose?"

A third body of responses to the book was neither as approving nor as disapproving as the first two. This was made up of non-Catholics (and some ex-Catholics) who were puzzled or bemused by the book, and by responses to it. On the one hand, they assumed that Catholics cannot "get away with" criticism of church authorities, and wondered why I had not been expelled. Non-Catholics are more certain that the church is authoritarian than Catholics are. Since they do not believe that the church is the people of God, and not simply the pope, they equate criticism of the part with condemnation of the whole. On the other hand, they wondered why I bother arguing about the church, which is for them an irrelevancy, though an interesting one.

These secular observers treated me as an anomaly, to be explained each in his preferred way. Martin Gardner in the Los Angeles Times said that I do not seem entirely nutty--I probably do not really believe, for instance, that a whale swallowed Jonah--so I must not be a Catholic after all. Richard Rorty in the New York Times thought I was right to criticize dishonesty in church leaders but wrong to expect anything else--if the church tried to tell the truth, he said, it would perish. Falsehood is its necessary foundation. They too had a different tone of voice in asking why I am still a Catholic. They meant, "How can anyone not clearly a nut remain there?"

Of course I do not believe that one has to be nutty in order to be a Catholic (though there are nutty Catholics, just as there are nutty secularists). Nor do I think church leaders must lie in order to keep their organization afloat (some have actually told the truth, and it made the bark more seaworthy). But it seems unlikely I will convince those who are sure that the Catholic church cannot be taken seriously. I will mainly address, therefore, those in the first two groups, those who do take the church seriously but wonder how I can still take it seriously after having criticized its leadership so pointedly.

When I was growing up, saying why one was a Catholic would not have focused so much on one's attitude toward the papacy. For Catholics in the middle of the twentieth century, the pope was a revered figure, but a distant one. We wondered why people like Paul Blanshard made so much of him, why Protestants and Others United for the Separation of Church and State were so sure that we followed his marching orders for the subversion of democracy. Actually, we didn't know much about the positions alleged against him. Our piety had other bases.