Yep, Halal is a thorny one. The problem is that, strictly speaking, if a food preparing area like a cafe or canteen wants halal certification it must meet some pretty strict criteria. For instance, as we all know, Muslims are forbidden from eating pork or pork products. However, to be halal, there must be no pork prepared or offered for sale anywhere on the premises. This is a bit tough on those of us who may like some bacon in our burger.
In my humble opinion, this is one area where some give and take is needed. Label the halal food accordingly for the benefit of the Muslims but hands off our pork snaggers. If they can't accept that then let them bring their own tucker to work or school, just as those with allergies and other special dietary needs already do. You can hardly expect a school or workplace to have a separate canteen for one group.
Likewise, holding back on celebrating Christian traditions like Christmas "to avoid offending non-Christians" is not necessary, in fact it is ridiculous in the extreme. Go to Israel or Saudi Arabia and see if they tone down their traditional celebrations for the benefit of the Christian minority- of course they don't and nor should they. As guests in a country minority groups should tolerate and accept the culture of the dominant group. In turn the majority can learn from these people and accept their practicing their cultural traditions.
Respect and Tolerance are both two-way streets.