@JohnAllenson:
Making English an official language and banning other languages is not going to pull the country together. If anything it's going to worsen conflicts between English and non-English speakers.
As to Common Culture, what common culture? They still can't come together on the cause of their Civil War more than 150 years ago. There's a big split between rural and urban cultures - I know people who are still bitter about the Rural Purge of 1970 when the tv networks cancelled a slew of popular programs with rural settings to cater to an emerging urban audience. Bipartisanship and 'common courtesy' have functionally vanished in American politics.
I think common culture goes back to the founding principles of the US: No government intervention preventing people from pursuing their best selves (to paraphrase broadly). Part of that includes rejecting thinking that prevents a group from succeeding – here are where the problems start.
My beef with Islam in the US is when practicing Muslims chose to wear the hijab by way of setting the tradition for their children. Tied to that is the sex segregation within their mosques. People can believe whichever version of the Spaghetti Monster they chose but the beliefs that teach young girls that they are less than men has to change in order to be in sync with a common western culture.
I think the fundamental differences in the two Americas -- or the two Wests -- is the degree the government is expected to help all peoples achieve their maximum. The current two extreme examples in the news are whether the government has the right to police language (hate speech/pronouns) and/or social norms (objectifying women, unconscious bigotry, etc. being crimes or not).
There are things we all believe but we've been steadily losing the ability to think critically to discuss them.
The language question is interesting because I live in a place that desperately wants to be bilingual. The US could easily be but chooses not to. One part of absorbing another language is that the thinking within does affects the culture. More English in Japan has meant a loss of the social roles here. Spanish seems the obvious choice in the states but I have no idea how that would affect the mental landscape. Perhaps be more passionate?