How do you decide who is a muslim btw?

Do you assume based on their birthplace?
Take my case. I am an atheist born in Istanbul. My turkish identity card has "muslim" written on it. I work as a researcher in a prestigious french university, and I contribute rather positively to the french society (I had many students, postdocs etc.). So you want france to kick me out, or not let me and my family into france based on what is written on my identity card? Very smart. I hate islam more than you do, believe me...

Or do you just ask? Do you think people who have no problem killing innocent people indiscriminately will have any problem lying to you about their religion? Muslims even have a word for it, it's called takiyye (in turkish spelling anyway). You are allowed to lie to further your religious goals.

So the rational thing is to not approach with a broad brush. And to try to identify who is dangerous and who is not, instead of trying to identify who is muslim and who is not, which doesn't immediately translate to violence or lack thereof anyway.

I guess this is the principle. But I agree that in practice the french are a bit too idealistic. They should probably come up with a better way of identifying the risks. Not everyone that can provide a translated cassier de judissiare from their home country is innocent in real life.