As the first biographer of Barack Obama, I have often found myself in a position where few journalists find comfort: defending the honor of a politician.

Yet, over the past 14 months, ever since the release of my biography of Obama, I have fielded countless questions about Obama that clearly have been based in ugly racial or religious distortion, and I have felt it my obligation to help set the record straight. In doing so, occasionally I have been accused of being an Obama sympathizer. But if that’s the price of spreading the truth, so be it.

On Saturday, Republican vice presidential candidate Sarah Palin accused Obama of "palling around with terrorists," a reference to Obama’s acquaintance with Bill Ayers, a former member of the Vietnam War-era militant Weather Underground. This Swift Boat-style smear attack has been going on against him for more than year—but until now, we’ve just never heard it directly from the mouth of a political opponent.

"Senator McCain and his operatives are gambling that he can distract you with smears rather than talk to you about substance," Obama responded.

At the risk of being accused again of Obama partisanship, I must say that there’s some truth in Obama’s response. An undergound effort to turn Obama into something he is not, to frighten Americans about a Manchurian candidacy, has been in place for some time. Fear, after all, is the most basic of human emotions, and political operatives have long used the power of fear to win elections, often with great success.

In various media interviews and on call-in radio shows, I’ve been asked such outlandish things as "How long has Obama been a Muslim?" and "How can he be president when he wasn’t born in the United States?" and "What does Obama have against white people?" Perhaps the most ridiculous came from a conservative radio host in California (of all places): "Why does Obama hate his white mother and idolize his black father?"

Just last week, a caller to a public radio show in Wisconsin pressed me endlessly about how Obama as a child had received Islamic instruction in a school in Jakarta. I answered that yes, he was exposed to this, but he also went to a Catholic school in Indonesia and certainly heard a few Hail Marys in his time, too—so what’s the point here? Of course, as the Reverend Jeremiah Wright episode revealed for all to see, Obama joined the Christian church in his early adulthood.

Nevertheless, as a result of such efforts, a Pew Research Center survey a few weeks ago found that only about half of American voters know that Obama is a Christian, with 13 percent saying that he is a Muslim.

I used to answer such questions with a bemused, yet unemotional response. But lately, I have become increasingly frustrated that such issues are still being raised more than a year-and-half after Obama launched his presidential campaign. To me, this says that either half of the voters are just not paying attention or, worse, they want to believe these distortions rather than the truth.

Obama’s hands are not totally clean when it comes to character distortion. Even Joe Biden criticized the Obama campaign ad that diminishes John McCain for not knowing how to send an email. It turns out McCain generally lets aides run his email because his war injuries make it difficult for him to type.

But a word to McCain’s strategists: I think that any sustained effort to de-Christianize or de-Americanize Obama eventually will backfire. I believe that, deep down, Americans want to cast their votes not on fear, but on knowledge. Particularly at this precarious moment in our history, when we are staring at the potential collapse of the country’s economic system, I have to think that voters will grow just as weary of these kinds of distortions as I have.