Barack Obama is not a Muslim.

We know this because he has told us so.

We know it because there is no credible evidence to suggest otherwise.

We know it despite a campaign of lies and whispers from various bloggers, pundits and head cases.

Barack Obama is not a Muslim. But, what if he were?

Same guy, same charisma, same inspirational idealism. But also, a Muslim. Not a crazy Muslim. Not a guy prone to strapping bombs to his chest in hopes of meeting virgins in heaven. A Kareem Abdul-Jabbar-type Muslim. A Dave Chappelle, Ahmad Rashad, Shaquille O'Neal-type Muslim. A guy you like and admire who just happened to be, you know . . . Muslim.

Would it matter? Should it?

The question bears answering because of the creepy, are-you-now-or-have-you-ever-been attitude toward Islam that seems to be seeping into the public dialogue lately. As in that campaign of lies and whispers that keeps showing up in my inbox -- claims that Obama won't salute the flag, took his oath of office on a Koran, belongs to a terror cell and other assorted idiocy.

NBC News anchor Brian Williams has apparently been getting the same e-mails. In moderating a recent Democratic debate, he asked Obama about rumors "that you are trying to hide the fact that you're a Muslim . . . "

The senator laughed a heard-that-a-few-times-before laugh. Then he replied that he is a Christian, that he is a victim of Internet rumor, and that he trusts the American people to "sort out the lies from the truth."

What bothered me is that, by its phrasing, Williams' question presupposed there is something wrong with being a Muslim. And Obama's answer left the presupposition unaddressed.

What if he was a Muslim? What then?

A 2007 Pew Research Center survey found that 43 percent of us have a favorable opinion of Muslims (make it Muslim Americans and the number rises to 53 percent). Which may sound not so bad, except when you compare it to favorable ratings of other religious groups. Jews, for instance, are at 76 percent. Even evangelical Christians manage 60. And that ranking for Muslims represents a 5 point drop since 2004.

It's no mystery why the nation's opinion of Muslims is becoming less favorable. In a word, terrorism. And frankly, Americans are right to fear Muslim fanatics who embrace violence as a means of getting what they want.

But see, the key word there is not Muslim. It's fanatic. Yet some of us still think Muslim is the brand name for crazy. Me, I think the only difference between religious fanatics here and in the Middle East is that Middle Eastern nations tend to be theocratic (i.e., the word of the holy book has the force of law) and to be intolerant -- sometimes, violently so -- of dissent. So no one dares tell them no.

I prefer my presidents -- regardless of religion -- reasonable. And sane.

But if Pat Robertson, to name an American Christian fanatic not quite at random, had the force of law behind him and the ability to silence those who disagree, don't you think he would be as scary as the scariest ayatollah in Iran?

I do. That's why I would never want him to be president. Which is not quite the same as saying I'd never want a Christian to be president. I just prefer my presidents -- regardless of their religion -- reasonable. And sane. That seems a fair standard.

Yet it's a standard some of us now discard. The ongoing whisper campaign against Barack Obama, against his very American-ness, is a shameful appeal to ignorance and fear. Against that, I offer a simple statement the world's most famous and well-loved follower of Islam made just after the Sept. 11 attacks.

"I am a Muslim, " said Muhammad Ali. "I am an American."

That says it all. Or at least, it should.