People in opposition to multiculturalism believe it:
causes a splintering of society
protects the immigrant's heritage
brings about a loss of national identity
causes too much diversity in society

The answer would be the loss of national identity.  The original settlers were from Europe.  Since it was established by Europeans and many of them want to maintain that status quo.  The latest influx of immigrants comes from Asia and their numbers are increasing.  With the increase of immigrants from other parts of the world, there is now more diversity and their number are increasing.  It could come to a point where they may become the dominant population and can mean the loss of national identity of the original settlers.

answer; collective security;