It has become tradition in this country to mark the anniversary of 9/11 with reflections on American values — founding principles including freedom, faith, democracy, and equality.

In keeping with this tradition, a report titled, "What it means to be American" was released this week by the Brookings Institution and Public Religion Research Institute examining the traditional American values of freedom, faith and equality through the lens of an increasingly diverse population.

In essence, the report finds Americans are united over many core values but are grappling with what those values mean and how they play out in a society comprising many religions, races and ethnicities.

For example, 88 percent of Americans agree that this nation was founded on the idea of religious liberty for everyone, including religious groups that are unpopular. They also agree that all religious texts should be treated with respect even if we don't share the religious beliefs of those who use them.

And yet the report also shows many Americans uncomfortable in the specifics of such religious tolerance, with nearly half saying Muslim values are at odds with American values, and 41 percent saying they do not believe Mormonism is a Christian religion.

To use immigration as another example, most Americans believe immigrants are hardworking people with a strong sense of family and community. But they are also divided over whether the influence of immigrants strengthens or threatens American society — an apprehension clearly reflected in the current debate over immigration reform.

"E pluribus unum," reads the Seal of the United States of America — "out of many, one." It is a theme that has repeated itself throughout history as successive groups have come to the U.S. and integrated into a society that wrestled with welcoming the newcomers while still preserving the founding principles of the country.

As the Brookings/PRRI report notes, the American pattern is to battle fiercely over whether a new group can ever "Americanize," followed by the new group embracing the underlying values and principles of democratic republicanism — in some cases even "more passionately than those who were here earlier and may have come to take them for granted."

Such was the case with Catholic and Jewish immigrants to the U.S. Americans have now largely discarded their historical suspicions of members of these two groups, and if history is any guide, they may be on their way to doing the same with regard to Mormons and Muslims — as well as new immigrant groups who bring new and unfamiliar traditions.

It is easy to bemoan the political and cultural battles that accompany the process of assimilation. And yet, these struggles themselves may be the essence of democracy. Democracy may, in fact, be at its strongest when expressed in a pluralist society, where various groups push, pull and ultimately demonstrate that in spite of social and cultural divides, it is still possible to come together to govern ourselves.

The American culture at which the 9/11 terrorists lashed out is rooted in the idea that people of all creeds and cultures are welcome, as long as they are willing to accept others as equal participants and abide by the rules of the American experiment. The process of struggling through strong differences — indeed, the very freedom and ability to work things out — was at the heart of the founding of America, and it is still very much a part of what makes us American today.