A while back I wrote a column about a traveling display featuring thousands of crosses representing the number of abortions every day in the United States. It's a powerful image. Too powerful, for some people: When folks at my church set it up on our lawn, vandals tore it down overnight and spray-painted "pro-choice" slogans. We weren't surprised. It was nothing new, really: Vandals had been doing similar things to the display across the country for years.

Here's something new, though. Thanks to the Internet, now the country can watch them do it, in broad daylight.

A recent online video shows one Roderick King tearing down crosses at the University of Wisconsin one sunny day, in full view of students with cell phones and a campus security guard. King, who happened to be a UW student senator, didn't have any legal authority to do what he did: He just felt like it. "This [abortion] is a right," he hollered. "You don't have a right to challenge it."

King was soon removed from the student Senate, and we could say he doesn't represent many people — that he's just a crank who's gotten a lot of attention. (The video's had more than 40,000 views to date.) Still, in some ways, he's not as unusual as we might like to think.

Not that many years ago, few people on a college campus would talk like King. Everyone was supposed to believe in free speech, open debate, the free exchange of ideas — or at the least, everyone was supposed to say they did. Not anymore.

Routinely these days, "pro-choice student groups refuse to debate their opponents despite the persistent efforts of pro-life students," writes Professor Jon A. Shields in the sociological journal Society. The groups themselves say as much. NARAL Pro-Choice America's Campus Kit for Pro-Choice Organizers is blunt: "Don't waste time talking to anti-choice people." So is the Pro-Choice Action Network: "Along with most other pro-choice groups, we do not engage in debates with the anti-choice," because — well, because "the right to abortion is not debatable."

The attitude isn't confined to campus, and it isn't confined to the abortion issue.

Case in point: At its annual convention last month, the American Psychiatric Association (APA) was scheduled to host an exchange — not even a debate, but a panel discussion — on "Homosexuality and Therapy: The Religious Dimension." It included two evangelicals: the Rev. Albert Mohler, president of Southern Baptist Theological Seminary and psychology professor Warren Throckmorton of Grove City College, speaking on (respectively) their pastoral and psychological approaches to people troubled by homosexuality. It also included Eugene Robinson, a high-profile openly gay bishop in the Episcopalian Church.

It could have been a good exchange. But it never happened.

Long story short, gay activists raised a huge stink about it. They'd long worked to block the APA from even considering that some people might turn from homosexuality, or that any views that didn't accept homosexuality per se deserve a discussion. They didn't intend to allow a trace of those views now. They raised the usual charges (the discussion could legitimize "homophobic views"). They lobbied Robinson to drop out, and days before the event was set to happen, he did, saying that "just my showing up and letting this event happen" lends "credibility" to the wrong ideas. That was that: The panel was dead.

And here's the really revealing part: The panel's organizer, David Scasta, is not only a former APA president, but he also identifies himself as gay. You'd think all that would give him a certain street cred with other gays. But in the eyes of some, he was now a mere tool of the enemy: "I got one e-mail from (Robinson) saying he thought I was being used by the other side, such as Focus on the Family," he said. Now Scasta can only think of what might have been. "It was a way to have a balanced discussion," he said. "We wanted to talk rationally, calmly, and respectfully to each other."

So much for calmness, rationality and respect.

What's behind this sort of brook-no-dissent political correctness? On the surface, it might seem like a supremely arrogant sense of conviction: We're so sure we're right that no one else even deserves a hearing. That's probably not the motive, though. People who are really confident of their beliefs don't shun debate. They tend to welcome it eagerly, especially when they recognize a lot of people disagree. (All the more reason the debate is necessary.) Look at the apostles: Peter and Paul and company walked right into pagan strongholds to make their case, precisely because their beliefs were so strong.

I think the real motive here, far from being sincere conviction, is closer to the opposite. It's defensiveness — or, in a word, insecurity.

The people who want to silence debate on abortion, homosexuality et al just can't stand to be challenged. They're threatened even by the existence of a respectable alternative to Enlightened Opinion. Partly, no doubt, that's because they're not sure they'd win a debate. But at the deepest level, I suspect it's because they're not sure they should win.

It all comes down to conscience. God has written His law onto every human heart (Romans 2:15). And that means all of us know deep down that things like abortion and homosexuality are wrong. Sometimes that knowledge gets buried very deeply, under many layers of justification and denial. And yet, that knowledge won't stay buried. The more outraged people get when they're reminded of it, the more desperately they're trying to suppress it.

That's why Christians should take a certain comfort in efforts to silence our voices. When we're speaking the truth in a civil, respectful way and still getting attacked for it, that doesn't mean we're being too provocative. It may just mean we're doing our job. We're setting the truth before as many people as possible, and letting them respond as they will. (He who has ears to hear, let him hear.)

We just have to keep doing it in the right spirit. When we're met with anger, the main thing to remember is not to respond in kind. When we debate, we're not trying to "win" — not for ourselves, anyway. There's no room for ego or competitiveness here. We want the truth to win out. We're not trying to beat anyone into the ground. We want the truth to set everyone free.