I've heard all kinds of different reports on who & why. I think "an anti-Muslim Christian" is just the best media controversy release right now. What's very troubling, is that Norway has been said to be the safest, and lowest crime rate country in the world, with the happiest population. And they don't really have immigrants of any kind.
I remember when they first caught McVeigh after the OKC Federal Bldg bombing... They trumpeted "MORMON" arrested for bombing. Turned out that he'd never set foot in an LDS church, and they said Mormon only because his father's uncle's maid's brother-in-law's ex-boss was Mormon, or something like that. In the media, anything goes to stir up trouble.
Charles