In another finding of Muslim American disconnect, fewer than half of all American Muslims believe that Arabs engineered the 9/11 attacks. Another third expressed no opinion or refused to answer.

That means that the vast majority of Muslims in America think ... what? That the U.S. attacked itself? That Israel did it?

While a majority of Muslims of all ages view al-Qaeda ``very unfavorably" (58 percent), an alarming number seem to be ambivalent. A whopping 27 percent said they didn't know how they felt toward the terrorist organization or refused to answer the question. An immigrant population that does not recognize the enemy of its adopted country cannot be said to have assimilated.

Nevertheless, the Pew study authors tell us that compared to Europe, we're in good shape. Yes, sure, ``there is somewhat more acceptance of Islamic extremism in some segments of the U.S. Muslim public than others,'' concede the authors. `` ... Nonetheless, absolute levels of support for Islamic extremism among Muslim Americans are quite low, especially when compared with Muslims around the world.''

In other words, presumably, we should be grateful that only 200,000 or so local Muslims support terrorism. In Europe, where many young Muslims are unemployed and alienated, things are much worse. True, but seldom does America measure success according to a things-could-be-worse standard.

Not so great is bad enough for reasoned alarm.

All of the study's conclusions depend, meanwhile, on whether one trusts its population figures, which Pew warns should be interpreted with caution. Since this was a telephone survey using only landlines -- and given that 48 percent of Americans age 18-29 use cells phones exclusively -- the number of young Muslims could be much higher than estimated. The truth is, no one knows how many Muslims live in the U.S. because the Census Bureau doesn't ask about religious identity. Muslim organizations put the figure at closer to 7 million based on mosque attendance.

If there are 7 million Muslims in the U.S., 30 percent of whom are young, 31 percent of whom do not forswear suicide bombings, then that could mean that as many as 651,000 young Muslim Americans sympathize with radical Islam and terrorism.

All things considered, it may be too soon to celebrate Muslim assimilation. Let's do hold the fireworks.