“Obama is a Muslim,” it said. “That is a FACT.”

As best I can recall — my computer ate the email — that was how the key line went in a reader missive that had me doing a double take last week. It was not the outlandish assertion that struck me but, rather, the emphatic claim of its veracity. We’re talking Shift-Lock and all-caps so there would be no mistaking: “Obama is a Muslim. That is a FACT.”

Actually, it is not a fact, but let that slide. We’re not here to renew the tired debate over Barack Obama’s religion. No, we’re only here to lament that so many of us seem to know “facts” that aren’t and that one party — guess which — has cynically nurtured, used and manipulated this ignorance for political gain.

Consider a recent trio of studies testing the effectiveness of fact-checking journalism. They were conducted for the nonpartisan American Press Institute, and their findings actually offer good news for those of us who fret over the deterioration of critical thinking and the resultant incoherence of political debate.

Researchers found, for instance that, although still relatively rare, fact-checking journalism has been growing fast and saw a 300 percent rise between 2008 and 2012. Also: Most Americans (better than 8 in 10) have a favorable view of political fact-checking. Best of all, exposure to fact-checking tends to increase respondent’s knowledge, according to the research.

But like stinkweed in a bouquet of roses, the studies also produced one jarringly discordant finding: Republicans are significantly less likely to view fact-checkers favorably. Among those with lower levels of political knowledge, the difference between Republican and Democratic voters is fairly small — 29 percent of Republicans have a favorable view, versus 36 percent of Democrats. Surprisingly, among those with higher levels of knowledge, the gap is vast: 34 percent of Republicans against 59 percent of Democrats.

The traditional rejoinder of the GOP faithful whenever you bring up such disparities in perception is that they mistrust “mainstream media” because it is biased against them. Putting aside the dubious validity of the claim, it’s irrelevant here. Fact-checking journalism is nonpartisan. One would be hard-pressed, for example, to paint PolitiFact as a shill for the donkey party given that it regularly dings Democrats and gave President Obama (“If you like your health plan, you can keep it”) its uncoveted Lie Of the Year award for 2013.

That being the case, one can’t help but be disheartened by this gap. What’s not to like about journalism that sorts truth from falsehood? What’s partisan about fact?

Nothing — you’d think. Except that, for Republicans something obviously is.

Perhaps we ought not be surprised given the pattern of party politics in recent years. On topics as varied as climate change, health care, terrorism and the president’s birthplace, GOP leaders and media figures have obfuscated and prevaricated with masterly panache, sowing confusion in the midst of absolute clarity, pretending controversy where there is none and finding, always, a ready audience of the fearful and easily gulled.

As political strategy, it has been undeniably effective, mobilizing voters and energizing campaigns. As a vehicle for leadership and change, it has been something else altogether. When you throw away a regard for fact, you throw away the ability to have effective discourse. Which is why American political debates tend to be high in volume and low in content. And why consensus becomes impossible.

The API statistics documenting the lack of GOP enthusiasm for fact-checkers, ought to tell you something. Who could have a problem with a fact-checker? He or she is your best friend if what you’re saying is true.

You would only feel differently if what you’re saying is not.

Leonard Pitts is a columnist for The Miami Herald. Contact him via e-mail at lpitts@miamiherald.com.