Even I, speaking as a complete lefty-looney, can see that multiculturalism is
a stupid idea. If you go to live in another country you accept that there
will be different social mores in that country that you have to abide by.
When you move to another country you have to play by their rules. An
Irish person wouldn't move to Iran and walk up the street half-naked or
bladdered drunk. Likewise, you can't travel half way around the world to
Ireland and act like you're still at home.
This means that certain things will not be accepted by the host
population here: circumcising your kids with a razor blade, beating them
with sticks, or refusing to give your seat on the bus to a heavily pregnant
or elderly woman, for example. And lots of other things besides.

Edit: I have heard liberals (even some of my friends) defend all of these things
on the grounds that they are acceptable in the perpetrators' native
cultures. I don't happen to agree