Those wondering why we haven’t seen any domestic incidents of terrorism since 9/11 might turn for some answers to the new Pew Research Center survey of 55,000 Muslims in America. Compared to Muslims in Europe, the survey found, American Muslims are less numerous, wealthier, better educated, more assimilated, and more mainstream in their political and religious views.

Two statistics jumped out at me. First, the Pew center found that there are only 1.4 million Muslims aged 18 or older in the U.S. (there are another 850,000 under 18), or about 0.6 percent of the population. (Other studies have suggested the figure is as high as 6-7 million.) That compares to 10 percent or more in some European countries. Second, only 2 percent of them are low-income, compared to 22 percent in Britain, 18 percent in France and Germany, and 23 percent in Spain. There is simply not a large, alienated Muslim underclass in this country as there is in so many European states.

That forms the backdrop to Pew’s findings about the American Muslims’ outlook on the world:

As many Muslim Americans as members of the general public express satisfaction with the state of the nation. Moreover, 71 percent of Muslim Americans agree that most people who want to get ahead in the U.S. can make it if they are willing to work hard. The poll reveals that Muslims in the United States reject Islamic extremism by larger margins than do Muslim minorities in Western European countries, when compared with results from a 2006 Pew Global Attitudes Project survey. . .

On balance, they believe that Muslims coming to the U.S. should try and adopt American customs, rather than trying to remain distinct from the larger society. And by nearly two-to-one (63 percent-32 percent) Muslim Americans do not see a conflict between being a devout Muslim and living in a modern society.

We can also cheer this finding:

Very few Muslim Americans—just 1 percent—say that suicide bombings against civilian targets are often justified to defend Islam; an additional 7 percent say suicide bombings are sometimes justified in these circumstances. In Western Europe, higher percentages of Muslims in Great Britain, France, and Spain said that suicide bombings in the defense of Islam are often or sometimes justified.

That’s the good news. But if you read the report carefully you will find some worrisome nuggets amid the generally glad tidings. For instance:

Consistent with the views of Muslims in other countries, fewer than half of Muslim Americans—regardless of their age—accept the fact that groups of Arabs carried out the 9/11 attacks. Just four-in-10 say that groups of Arabs engineered the attacks. Roughly a third (32 percent) expresses no opinion as to who was behind the attacks, while 28 percent flatly disbelieve that Arabs conducted the attacks.

Of even greater concern is that the most radical part of the Muslim-American population tends to be younger people (18-to-29 year-olds, who form a third of the total Muslim population here), suggesting that some of the positive trends noted above may disappear over time. Pew finds that

Younger Muslim Americans report attending services at a mosque more frequently than do older Muslims. And a greater percentage of younger Muslims in the U.S. think of themselves first as Muslims, rather than primarily as Americans (60 percent vs. 41 percent among Muslim Americans ages 30 and older). Moreover, more than twice as many Muslim Americans under age 30 as older Muslims believe that suicide bombings can be often or sometimes justified in the defense of Islam (15 percent vs. 6 percent).

Native-born African-American Muslims are another area of concern:

More generally, native-born African American Muslims are the most disillusioned segment of the U.S. Muslim population. When compared with other Muslims in the U.S., they are more skeptical of the view that hard work pays off, and more of them believe that Muslim immigrants in the U.S. should try to remain distinct from society. They also are far less satisfied with the way things are going in the United States. Just 13 percent of African American Muslims express satisfaction with national conditions, compared with 29 percent of other native-born Muslims, and 45 percent of Muslim immigrants.

Bottom line: The U.S. has done a much better job of assimilating Muslims than has Europe, and this means that we have a much lesser risk of homegrown terrorism. But lesser doesn’t mean zero, and, as we’ve seen in Iraq, it doesn’t take many fanatics to cause great damage. Moreover, as on 9/11, foreign groups can always smuggle in their operatives from abroad. So we shouldn’t get complacent. But we can take pride in America’s continuing accomplishments in assimilation, notwithstanding the fears of the nativist right.