Also, are those refugees really contributing to the economy? From what I've heard, they're good at taking advantages of benefit systems in the western countries, which have recently been downright socialist (that's why they don't care much about Poland, we got rid of our socialist regime in 1989 ).
It's not about what they're doing now, it's what they or their children are going to do in ten years. For one, our populations are shrinking, which means we need more people to run our economy. Second, Refugees are usually motivated enough to get started on a new life; if given the chance, they're more likely than not to be net contributors to the economy in the short or medium term.
I mean I know it's a tiny tiny fraction (the first few numbers I've googled suggest a couple thousand across Western Europe) but how can you pretend it's not significant? Those people don't exist in a vacuum; they're a symptom of some larger problem, and whatever lead to them being so estranged from their home country is a big component of that problem. You can't credibly say that there's no problem in the relationship between Europe and a segment of its immigrant population and then use that as leverage to call people delusional bigots.
It really isn't significant. Sure, it would be better if radicals couldn't recruit as easily as they can, sure, we could do a better job at making refugees welcome and give them ways and means to become citizens, but taking an attack like this one as a signal that we need to start turning away more people? That we need to be more vigilant, less trusting towards these people? No. That, for me, is a step too far. Radicals will
always be able to recruit. Terrorists will
always be able to inflict damage. As free and open societies, that's what we have to live with.