My cleaned up responses to a typical multiculturist are below. You can figure out what his concerns were from my replies. My responses show how a reasonable culturist can respond to an outraged multiculturalist.
You define racism as structural oppression and so say America is racist. Your concerns have merit. We should make sure that economic and educational opportunity are as available to everyone as possible. If we find an bank that does not lend money to people simply due to their race, that bank should - in my opinion - be fined. Racism can divide us, creates bitterness and is dangerous. We need to do what we can to combat racism.
However, you greatly underestimate the power of culture. I live in America. Here, the lower academic achievement rates of Latinos and Blacks often gets cited to boslter your claim that ours is a "structurally racist and oppresive" society. This conclusion is partially based on the correct idea that differing levels of achievement don't have anything to do with race. But people who then conclude that America is racist and oppressive routinely fail to consider the possiblity that culture is important.
Culture is important and can account for different levels of achievement. Kids in Tapei do much more homework than white kids in Minessota (Harold Stevenson's work). Individuals vary, but some cultures value educaton more than others. That can be seen objectively in statistics on drop-out and teen pregnancy rates as well as hours spent doing homework. Even if there was no racism anywhere in the world, cultural diversity would result in very different levels of educational and economic achievement. Acts of individual racism exist, but the achievement gaps are almost entirely the result of cultural diversity.
Multiculturalists say that they believe in diversity. They think it relates to food, fashion and festivals. But they don't think cultural diversity could possibly account for something as important as economic or educational achievement. Multiculturalists think diversity is shallow. Culturists know that cultural diversity is not only cute and inconsequential.
Culturism's anthropology chapter and looking at world events show us that not all cultures value individualism, female rights, fighting racism, the separation of church and state, an achievement ethic or even democracy. You say embracing humanism is the way to get out of wars. If all other cultures were to stop competing, I'd be happy to. The fact is that Islam is competing with us ideologically and China is competing with us economically. Our values are not universal norms and so cannot be taken for granted. Because diversity is real, culturism is necessary.
Sometimes a group's statistics do cause innocent individuals to be singled out. That is unfortunate. But denying that cultures have traits that should be addressed and calling society racist does not help. When statistics show muslim terrorism has stopped, we can stop profiling at airports. When Latinos do better in school, we can stop having programs designed to help them. Unfairly stereotyping individuals is a legitimate concern, but ignoring cultural diversity doesn't help subcultures and endangers Western nations.
Finally, culturism and nationalism are not the same thing. Nationalism is content-free. Western culturism relies on Western cultural traditions through the ages to ground itself. Nationalism coud be used to advocate actions, such as genocide, which violate our cultural traditions. Culturism has deep philsophical and historical traditions, achievements and standards to uphold and honor. Nationalism is shallow and sometimes dangerous. Culturism provides ethical guidelines and is necessary for our safety and success. Nationalism and culturism are not synonymous.