Roger Cohen expresses the parallels with Islamism very well:
European Christendom in this context is a mirror image of the idealized caliphate of Osama bin Laden. It is a dream-world cause through which to enlist the masses in apocalyptical warfare against an “infidel” enemy supposedly threatening the territory, morals and culture of an imagined community of devout believers.
This particular Christian Europe — the Continent is overwhelmingly secular for reasons that have nothing to do with a growing Muslim presence — is just as fantastical as a restored 7th-century dominion of the caliph. Bin Laden inveighed against “crusaders.” Breivik attended a 2002 meeting to reconstitute the Knights Templar, a Crusader military order. This is the stuff of video games — except that it kills real teenagers of all faiths.
What has become clear in Oslo and on Utoya Island is that delusional anti-Muslim rightist hatred aimed at “multiculturalist” liberals can be just as dangerous as Al Qaeda’s anti-infidel poison: Breivik alone killed many more people than the four Islamist suicide bombers in the 7/7 London attack of 2005.