I don't understand why people think this is racist. I think 'rayiner is just saying that people have culture. People get their culture from family, school friends, local activities like scouts, church or sports clubs, online communities, mentors. In neighborhoods populated by immigrants from the same immigration wave, local culture can persist for a long time and will only become the same as the average US culture after more than a century.
Religion is likely to stay for longer, and will change to become more like average US culture slower. For example, I don't know if and when a mild American version of Islam will develop which is more adapted to live in harmony with other cultures found in the US.
Racism is when you stereotype people based on their racial characteristics. Calling people of a certain race or ethnicity "groups" instead of "races" when making this judgment doesn't make it not racist.
Putting that aside for the moment, the argument rayiner made, and that you appear to be supporting, is that if you bring too many foreigners into a country, it will change the cultural makeup of that country. It's an argument that seeks to exploit people's fears. It's not a new argument, and it's a largely discredited one. People who make this argument have to anticipate at least the following questions and provide some very difficult answers to them:
1. What exactly is American culture?
2. Is American culture homogeneous? If not, how do you know where immigration will disrupt existing culture, and where it won't?
3. How will you know when American culture is disrupted because of immigrants as opposed to intrinsic forces?
4. How much immigration is too much? How do you know?
5. Which immigrants do you believe are OK to permit into the country, in what numbers, and where?
6. For any potential individual immigrant, how do you know this immigrant will or won't assimilate?
7. How long should an immigrant be given to assimilate? What will assimilation look like for them? What does the bar for "good enough" assimilation look like?
8. Why isn't conformance to our laws sufficient for an immigrant to be accepted?
9. Should new immigrants be Judeo-Christian? If so, how do you square that with the First Amendment's freedom-of-exercise clause? What about all the Muslims already in the USA? Have they adversely impacted America? If so, how?
10. How do you think about the difference between a Black person already in the USA (see question 2) and a new African immigrant?
11. Do the impacts of immigration--particularly of Africans--manifest differently in the Americas than they do in other countries, say, in the UK? If so, why?
12. What about native-born Americans who don't conform to whatever American culture is (see question 1)? Should we eject them?
When I ask people these questions, they invariably end up falling all over themselves. People don't think about immigration rationally; they fall back to primitive "in-group" and "out-group" thinking and engage in "otherism." Sometimes it's religious hatred; sometimes it's racial hatred; other times it's class hatred. I encourage anyone who believes that immigration causes problems figure out for themselves the answers to the above questions and how they would craft a policy that serves everyone better, and not one that just suits their own prejudices.
Religion is likely to stay for longer, and will change to become more like average US culture slower. For example, I don't know if and when a mild American version of Islam will develop which is more adapted to live in harmony with other cultures found in the US.