If there is too many foreigners coming in then there will be a problem due to decreased jobs, food, facilities, etc, and putting more financial pressure. This is not racist, this is the reality. One who has too much tolerance and does not manage it correctly, now that is threatening. Everything has a limit.
i live in the US. everyone that lives here was an immigrant or had family that immigrated here at some point. i have no problem with immigrants that come here legally. even illegal immigrants just want the best for their family. that's why they come here. even though it may cause problems/controversy, i feel bad for them. no one has "problems" with european immigrants to the us (legal or illegal) people are just worried about more minorities coming into "their" country, which is sick and disgusting.
Multiculturalism can mean a variety of things depending on the context.
If you are just asking about immigration, then I have no problems with it. If anyone wants to come here for a better life, they usually are making valuable contributions to the nation as a whole. So, why not?