I was in Dubai during Ramadan the other year. The advice in the hotel was that as a non Muslim nobody expects me to fast.
However, when some poor sod is thirsty and sees me guzzling a bottle of water, it can't be nice for them so drink discreetly in the cordened off places made available in most hotels and shops.
A Muslim friend sent us a Christmas card and we reciprocated. Neither of us are Christians but celebrating Xmas is a British thing every bit as much as a religious one.
The only thing to be offended by is fundamental Christians claiming Xmas should revert to some religious festival. Fine. Enjoy. I'll enjoy it on my way and the little baby Jesus isn't a necessary part of it. Family, food, wine and the giving of presents. That's enough for me.