Right now in my country (the US) it would be more the threat of Latin America overtaking the US culture (though there is plenty of fear of Muslims too), even though we're the ones who arm them, buy the drugs that keep their cartels in power, and maintain thugs in power if they simply do our bidding (or destabilize democratically elected governments who serve the interests of their people above US interests).

Here in the US we're supposed to hate and fear each other because someone is going to take our jobs, or change our language, or rob us.

Not long ago it was my people (African-Americans) the white americans were supposed to fear. That's why "white" was created as an idea. Before that there were landowners and those who worked for landowners. But then newly freed African slaves started working with European descendant indentured servants and sharecroppers too effectively, so "white" had to be created to separate the poor and increase the relative power of a much smaller group of wealthy landowners, all of who happened to be European descendants.

"You're more like us than like them," they told the poor "whites." "You should support our interests so that someday you can be like us, instead of becoming more like them. You don't want to become more like THEM do you? You see how much worse we treat them than the way we treat you. Things could get so much worse."

This has worked for a long time, and continues to work.

And yet it is also true that while a culture is strengthened by an influx of differing viewpoints, genetic stock, etc. it can only digest but so much at a time. It absolutely can create a cultural crisis and exacerbate existing economic and environmental issues if too many people from an "alien" culture swarm another culture in a short period of time.

I’m sure you can see the insanity of a foreign policy that revolves around bombing middle-eastern countries into the stone-age and then inviting everyone to live in Europe....

Yes, I do see the insanity of such a foreign policy, and many of the same people saying "don't criminalized being a refugee" are also saying "don't bomb them out of their homes, and we'd rather they stay where they are now." It's not so black and white in all minds. There is a great deal of complexity being considered from some mental frameworks.

That said, some "sides" of the issue are more wrong than others. That's real. Some are more dangerous than others. It's hard to avoid letting the perfect be the enemy of the good when both are so terrible. And yet, there is such a thing as worse.

And this is the difficult situation we're in. All the options are quite horrible, and yet we must act.