No matter what Juan Williams says, even the dumbest terrorist in the world wouldn’t wear a robe and turban on a plane. Williams’ crime wasn’t just his comic bigotry but his ignorance.

Let’s imagine the thoughts of a suicide bomber. He (or she) is probably sweating profusely, probably trembling as he waits to board. Not only is he about to try to kill scores of people, but these are the final moments of his life.

And as he’s getting dressed that morning—perhaps for the last time—would he bypass his button-down shirt and jeans and reach for a flowing robe? Aside from the trembling, the uncontrollable perspiration, and that damned churning in his stomach, does he want to guarantee he will be “randomly” selected at the metal detector for extra screening?

“They seek to blend in, not stand out,” said Bruce Riedel, a former CIA officer and terrorism expert. “The 9/11 hijackers did not wear robes, nor did the Mumbai terrorists.”

When NPR’s Williams made his controversial comment last week about getting nervous when he sees people in “Muslim garb” on a plane, it wasn’t just his prejudices that were appalling. It was lack of understanding that runs so deep it turns into a dangerous underestimation of terrorists’ intelligence.

Even the hapless Faisal Shahzad wasn’t wearing a turban and riding a camel through Midtown Manhattan.

Even as bloggers and erstwhile politicians work themselves into a frenzy over Williams’ firing, they continue to miss the underlying point. Failing to understand the enemy is the most dangerous threat to American security there is. Isn’t that a basic rule of war? If you’re going to fight terrifically difficult, possibly futile, wars on terror, you may as well do it smartly.

And were Williams’ comments just an isolated incident, it wouldn’t be so worrisome. Earlier this week, a NATO official anonymously told CNN that Osama bin Laden and his deputy were not actually living in a cave, but much more comfortably—perhaps even in an apartment with indoor plumbing!—in Northwest Pakistan. The media howled and demanded to know why we haven’t caught him yet. (Whatever happened to Osama’s dialysis machine anyway? You’d imagine that would be tough to drag around in unreachable caves for nine years.)

• Roja Heydarpour: Not All Terrorists Are Stupid, JuanIs it really all that shocking that the head of the most powerful terrorist organization in the world, the mastermind behind attacks that brought down the Twin Towers that Tuesday morning, would have not only the wherewithal and local connections, but the money to live however he chooses? Just because he doesn’t operate under the rules of a sovereign nation does not make him any less sophisticated. In fact, he has to be even more resourceful.

“Osama bin Laden is alive and in charge, not from a cave, but with a computer,” Riedel said. Al Qaeda operatives “are agile, adaptive and learn from their mistakes.”

Now, of course not all terrorists are genius. Not even close. There are generals, and there are soldiers. There are criminal masterminds, and people who are something less than that.

There are the Times Square bombers of the world, who make a hash of their missions. Though even the hapless Faisal Shahzad wasn’t wearing a turban and riding a camel through Midtown Manhattan.

In the end, it’s all ridiculous. Not all terrorists live in dusty shacks without running water. Many read books and the Internet. They study. They prepare. When the next terrorist tries to strike, he probably won't walk into an airport wearing a turban and carrying a grenade, screaming “Allah Akbar!” at the top of his lungs.

Roja Heydarpour is an editor at The Daily Beast. She has reported for The New York Times and The Times-Tribune.