We keep hearing that democracy won't work in Iraq and that Muslim countries cannot join the modern world because the problem of sectarian division runs too deep. Often it is simply presumed that the Sunni-Shia difference is so profound and contentious that there is simply no hope for a country like Iraq to hang together, and Americans may as well pack up the tent and move out.

Most of the time these arguments are pure ethnocentrism, a projection of Western views of religious warfare onto the Islamic world. But historian Bernard Lewis notes that there is nothing in Islam that compares with the bloody clashes between the Protestants and the Catholics in Europe. Theologically, there is virtually no difference between the Shia and the Sunni. Contrary to the repeated assertions of Congressman John Murtha and others, the Shia and the Sunni have not been fighting for centuries. Only two decades ago they were fighting side-by-side to repel the Soviet Union from Afghanistan.

Mahmoud Ahmadinejad's defense of the Khomeini regime during his recent New York trip reminds us that Islamic radicalism is not exclusively a Sunni or a Shia phenomenon. Iran is a Shia country, and Hezbollah, which periodically dispatches its rockets into Israel, is also Shia. By contrast, Hamas is largely Sunni. Al Qaeda is Sunni. The Iraqi insurgents launching suicide attacks against American soldiers are overwhelmingly Sunni.

I wasn't in the audience at Columbia, so I didn't get to pose a question to Mahmoud Ahmadinejad. I would have guessed that he is pretty capable of answering questions about the Holocaust ("at least we didn't do it") and Iran's nuclear aspirations ("entirely peaceful"). Even his stated goal of wiping Israel off the map doesn't break the register on my surprise-o-meter. Nor would I be entirely astonished if there are many leaders in Israel who'd like to see today's Iran wiped off the map.