The prescient Rod Dreher comments on Europe’s response to being attacked by Islamic terrorists, and though he doesn’t mention rousing choruses of Imagine, he might just as well have done:

One of these days — sooner rather than later — Europeans will tire of hashtags, candles in the square, and diversity-is-our-strength lectures from their leaders. Then what?

The Jihad Runs From a Peace Sign. In Candles.
Then what. Dreher hints at an outcome earlier on in his blog piece, after hearing a list of potential Jihad targets from an Italian intelligence source:

If those Islamic terror cells activate themselves, Europe is not only going to have to worry about its train stations and airports. This would be all-out guerrilla war, and nobody would be safe.

Get Used to a Lot More of This
With that, the boom would come down on Europe’s post-war liberal society, and its freedom, to say nothing of Aleppo coming to a city near you.
One major power, Russia, appears to take this seriously, perhaps because the Jihad’s on its borders, but in Western Europe that border’s blurred, if it’s there at all. And after the hashtags, peace signs and John Lennon songs have bitten the dust, what then?
I’m not a betting man, but I wager the result won’t be a whole lot of peace, love and music. You can read the whole thing here.

ISIS Laughs.