Ordinarily, I admire people who tell pollsters they "don't know" the answer to some poll question. And I'm often amazed by how few of them there are, because for many poll questions, "Don't Know" is the only correct answer. For example, there are questions asking for predictions about the unknowable future: Will newspapers survive? Will there be another terrorist episode in the United States in the next year? Will the Tea Party be a force in the 2012 election?

Then there are questions that require expertise to have even a coherent opinion about them--let alone the correct one. Are we headed for a double-dip recession? Is the hot weather this summer a sign of global warming? This is not meant to be patronizing. Nearly everyone has expertise about something-or-other that even Paul Krugman may not share. But people seem happy to answer pollsters' questions on any subject that is thrown at them.

However, I am depressed rather than impressed about how many people say they "don't know" what President Obama's religion is. Weirdly, that number is rising. It was 36 percent of the population in a Pew poll in March, and has risen to 43 percent in August. If you believe this poll, in other words, at least seven percent of the American population used to know what Obama's religion is, but have forgotten.

In all, 56 percent of the population think they know what Obama's religion is. Thirty -four percent really do know, or guessed correctly. Twenty percent--how can I put this delicately?--have their heads up their asses. (This includes 18 percent who know he's a Muslim and two percent who know that he is something else. Jewish, perhaps.) The 34 percent who know that Obama is a Christian is down from 47 who knew this in March. Meanwhile the percentage who know that he is a Muslim has jumped from 12 percent to 18 percent. I suppose there is some comfort in the fact that people are learning that Obama is a Muslim at only half the rate at which they are forgetting that he is a Christian.

In 2004, 26 percent of those polled said that President George W. Bush relied "a great deal" on his religious beliefs in making policy, 38 percent said "a fair amount," and 53 percent thought that this was "the right amount." By contrast 43 percent in 2010 think that President Obama relies "not very much" on his religious beliefs, but 48 percent think this is "the right amount." Apparently, people wanted George Bush to rely on religion, but want Barack Obama not to. Or something.

How is it possible that so many people could be so mistaken about the president's religion? Some say that all questions about the president are basically one question: How do you like what he is doing? If he keeps getting more unpopular in this predominantly Christian nation, his "Christian" rating will go down and his "Muslim" rating will go up. If he gets more popular, more people will remember that he's a Christian.

But what if you take the poll seriously and assume that the people questioned took it seriously, what's the explanation? Is it the failure of civic education in our public schools? Is it right-wing nutballs on the radio?

I blame pollsters themselves. They have created a world where everything is an opinion, nothing is a fact, everybody is entitled to an opinion, and every opinion is equally valid. The Pew press release about this latest poll is scrupulously neutral. It talks about "the view that Obama is a Muslim," as if it is just like any other view about the president's religion. Not a word in it hints that there might be a right answer and a wrong one.

Pew may have felt that telling people in its press release that Obama is a Christian is just too ridiculous and unnecessary. But, according to the latest Pew poll, it isn't.

Update: A correction was made to the fourth paragraph clarifying the author's interpretation of the Pew data