Church teaching is the same always and everywhere—except when it isn’t.

Using the words “pope” and “condom” in the same sentence is bound to draw attention; when it’s the pope himself using the latter word in a sentence of his own, the world takes notice.

So it did when, in excerpts of his new book-length interview Light of the World (Ignatius), Pope Benedict XVI acknowledged the moral possibility of a person with HIV using a condom to prevent the infection of a sexual partner: “[The church] of course does not regard [condoms] as a real or moral solution,” said Benedict, “but, in this or that case, there can be nonetheless, in the intention of reducing the risk of infection, a first step in a movement toward a different way, a more human way, of living sexuality.”

Reaction to the pope’s remarks ranged from relief among Catholic health care providers in the most AIDS-ravaged parts of the world—who have hoped for such a statement—to condemnation of the media for focusing on this one small part of the pope’s book. But since the Vatican approved the excerpts for publication just prior to the book’s release, it seems likely that the Holy See anticipated the furor. The remarks even came complete with a Vatican press release the day after, which, while insisting the pope’s remarks were made “in a colloquial, and not magisterial, form” and denying any change in church teaching, confirmed what the pope said.

There was nonetheless pushback from many quarters. Papal friend and publisher Joseph Fessio, S.J. assured ABC News that “we will not see a change either in this papacy or after this papacy.” The newly elected president of the U.S. bishops’ conference, New York’s Archbishop Timothy Dolan, put it more bluntly in an interview with The New York Times: “You get the impression that the Holy See or the pope is like Congress and every once in a while says, ‘Oh, let’s change this law.’ We can’t.” Except sometimes the pope does.

This change-phobia among many Catholics is perhaps the more interesting dimension of the story. Despite the fact that church history is littered with changes in not only custom and practice but moral teaching (slavery, torture, and usury, to name a few), acknowledging them is almost anathema. But one has only to look to the earliest chapters of the New Testament to find an example.

Consider St. Paul: In his letters he rarely refers to the teachings of Jesus, but what he does cite he feels free to change. Paul acknowledges when writing to the church in Corinth, for example, that Jesus forbade divorce. Yet, when faced with converts whose non-Christian spouses didn’t want to live with them anymore, Paul first restates Jesus’ command in four different ways but then modifies it: “If the unbelieving partner separates, let it be so; in such a case the brother or sister is not bound” (1 Cor. 7:15), therefore free to remarry. Faced with a new problem, Paul adapts. Jesus said no divorce; Paul says no divorce, too—unless there is a really good reason.

That is a precedent all Christians should be thankful for. Without it Christianity would likely have remained a fringe movement on the edge of Judaism if it didn’t die out altogether. Providentially Paul and generations after him had the good sense to adapt the demands of the gospel to the needs of time, place, and culture, even when that meant making a “concession,” just as Benedict has now done as well. His predecessor Pope Paul VI could not have foreseen the ravages of AIDS when he wrote Humanae Vitae more than 40 years ago, and one wonders if he might not have carved out an exception himself had he been aware of what the future would hold.

It is unfortunate, then, that so many Catholics are unwilling to acknowledge the possibility of change. Ours would be a brittle doctrine indeed if it could not respond to the needs of people in danger, and our faith is on shaky ground if it can’t survive a certain amount of modification, reevaluation, and even the occasional about-face. We would all be better served by a thoughtful, theological—even papal—acknowledgment that, as a pilgrim people, our grasp of the truth is conditioned by time and circumstance.

That doesn’t mean we lack the truth or that every change is a good one. It just means that the fullness of truth, as a dimension of the divine mystery, is beyond our human comprehension. Our salvation, after all, isn’t predicated on being right about everything all the time. In fact, thank God, we’re still saved even when we’re wrong.