Muslim immigrants in the west have very similar problems: they don't assimilate, their loyalties are brought into question, they only eat "halal" food, etc.
"if you go to a university campus good look finding a single muslim student"
is utter bullshit. There's nothing friendly I can reply here, you just pulled that out of your rear end. Stating it that broadly you were _obviously_ completely wrong, but from my (of course biased, limited) experience in Germany muslim students are actually common. A minority? Yes, but I guess ~real~ christian students are underrepresented as well.
What I said is a fact, if you don't believe it go and make a survey yourself or something. Honestly your reply is just childish.
Have it occurred to you guys that you may be talking to a muslim?
You probably aren't running into many devout/conservative type muslims who pray during the day or wear appropriate regalia. By that logic, you could argue that Catholics are underrepresented, because nobody is carrying rosary beads or confessing sins daily.
For instance, they don't drink, so you're not going to find them in bars (where a lot of socialization occurs). They don't marry much into other religions (even if some types of marriage are not prohibited, they're still frowned upon socially). You're not likely to see them date at all (though it depends on how devout they are).