Guilt by association, which the left condemned when they claimed to be its victims in the Truman-McCarthy era, has been used by the left since it sought to tie the assassination of JFK by a Marxist from the Fair Play for Cuba Committee to the political conservatism of the city of Dallas.

But Europe’s left will encounter difficulty in equating criticism of multiculturalism with neo-Nazism. For Angela Merkel of Germany, Nicolas Sarkozy of France and David Cameron of Britain have all declared multiculturalism a failure. From votes in Switzerland to polls across the continent, Europeans want an end to the wearing of burqas and the building of prayer towers in mosques.

The flood of illegal aliens into the Canary Islands from Africa, into Italy from Libya and Tunisia, and into Greece from Turkey has mainstream parties echoing the right. The Schengen Agreement itself, which guarantees open borders within the European Union to all who enter the EU, is under attack.

None of this is to deny the presence of violent actors or neo-Nazis on the European right who bear watching. But, awful as this atrocity was, native born and homegrown terrorism is not the macro-threat to the continent.

That threat comes from a burgeoning Muslim presence in a Europe that has never known mass immigration, its failure to assimilate, its growing alienation, and its sometime sympathy for Islamic militants and terrorists.

Europe faces today an authentic and historic crisis.

With her native-born populations aging, shrinking and dying, Europe’s nations have not discovered how to maintain their prosperity without immigrants. Yet the immigrants who have come—from the Caribbean, Africa, the Middle East, South Asia—have been slow to learn the language and have failed to attain the educational and occupational levels of Europeans. And the welfare states of Europe are breaking under the burden.

Norway, too, needs to wake up. From the first call for help, police needed 90 minutes to get out on the island in the Oslo lake to stop the massacre by the coward, who surrendered as soon as the men with guns arrived. Apparently, Breivik wanted to be around to deliver his declaration of European war in person. Yet, if convicted of the 76 murders, Breivik can, at most, get 21 years, the maximum sentence under Norwegian law.

Norway is a peaceful and progressive country, its leaders say.

Yet Norway sent troops to Afghanistan and has participated in the bombing of Libya, where civilians have been killed and Moammar Gadhafi has himself lost a son and three grandchildren to NATO bombs.

As for a climactic conflict between a once-Christian West and an Islamic world that is growing in numbers and advancing inexorably into Europe for the third time in 14 centuries, on this one, Breivik may be right.