I have read (correct me if I’m wrong) that Muslims are not supposed to “hang out” with non-muslim folk, or eat their food.
My community had a neighborhood picnic, and our muslim neighbors not only showed up but were eating some of the pot luck food.
This is one common, and probably correct given the actual wording, interpretation of the Koran.
However, it should be pointed out that various Christian and Jewish groups have similar doctrines, and there are passages in both Testaments of the Bible that can be applied to justify it.
As far as food goes, I presume a strict Muslim would not eat food unless he was sure it was halal, any more than a strict Jew would not eat food unless sure it was kosher.
Kosher, at least in the stricter interpretations, is a lot more stringent than halal.