Multiculturalism is a meaningless word to be honest, it sounds great, like a United Colours of Benetton advert, but it really doesn't mean much, because who defines 'culture'?
In the US, there is Freedom of Speech, to take my earlier example, pro- and anti-abortion. They are, by and large, secular groups, those that attend rallies etc, would not go out for a drink with the 'opposite team' afterwards, they are ideologically opposed enough for it to define their entire relationship.
However, those who simply take the position as a belief, and don't try to make it part of their culture, can often be friends for years without the subject ever coming up, and can still function perfectly well and respectfully as friends afterwards.
The people who create the divides between the cultures are usually the loudest advocates when it comes to defining it, so multi-culturalism is pointless, because it depends on a few peope defining each culture instead of society amalgamating the two as it has done so succesfully countless times in the past in just about every country in the world.