The subculture around Norwegian black metal in the early 1990s was strongly associated with a string of arsons and murders. In that regard, it can be vaguely compared to hip-hop in the era of the East Coast/West Coast beef, but while there was a clear underpinning of ethnic and economic disenfranchisement there, it seems like the black metal inner circle emerged out of a socioeconomically comfortable background. What specific factors about early 90s Norway (if any) could have led to this wave of violence?
It is often hypothesized that when Mayhem vocalist Per Yngve Ohlin committed suicide, the scene became a lot darker and real. Mayhem's semi official album "Dawn of the Black Hearts" was released with a cover featuring a picture of none other than Ohlin's dead body, with shotgun and all, taken by Mayhem guitarist Øystein Aarseth. They used his suicide note as song lyrics and the band members made necklaces with pieces of his skull, given to "worthy musicians." Oystein used the image to further Mayhem's dark image.
After the Mayhem incident, Øystein had allegedly became so enthralled with this dark image that he kept it going. He opened a record shop, Helvete ('Hell' in Norweigan), and it became a stronghold for the Black Metal scene. Many young musicians and bands had become obsessed with the same ideas Øystein had and transformed their Death Metal bands into Black Metal bands, with the same anti-religion and totalitarian ideas that Øystein had. The satanic image was there, but they concentrated more on being evil than any real philosophy and thus church burnings and murders came with that.
Sources: Sam Dunn, Director. Metal: A Headbanger's Journey (2005)
Michael Moynihan, Author. Lords of Chaos (1998)
Edit: Fixed mix up about Ohlin being guitarist, when he was in fact a vocalist.
As unreliable as Varg Vikerness may be, you might get satisfactory answers by looking up his videos where he speaks of the Norwegian Black Metal scene during '91 - '93.
The documentary "Until the Light Takes Us" and Fenriz of Darkthrone are also good sources to answer this question. Members and fans of the scene have pointed out that the book Lords of Chaos is not entirely reliable.