Being totally against the EU, i think full on nationalism is wrong too. We life on one big spaceship and with that, we should have one organizing (not governing entity) like the UN was once meant to be.
Germany has a Muslim minority. And Cyprus has 25%. I don't think Religion is a point here at all, culture definitely is.
Also, your mistaking Christianity - which is doing just fine in the western world, probably better than ever - with its degenerate form of fundamentalist groups, based mostly on hate, eg homophobia. This is most visible in Poland - which is very Catholic, and definitely not Christian.