I shall quote from the BBC:
He said his operation had not been aimed at killing as many people as possible but that he wanted to create the greatest loss possible to Norway's governing Labour Party, which he accused of failing the country on immigration.
I'd like to see him say that to the family, friends and relatives of the people he shot dead.
He is a 32-year-old born Norwergian, with religious background (Christianity) and views the world in a way that the multiculturalism is a bad thing that must be opposed at all cost. His main issue seems to be with Islam and how it spreads in Europe, discarding the original European culture. How this leads to killing of 91 children in social democratic camp is a question, though.
Multiculturalism takes time to work and requires constant maintenance. Look at Singapore. We've somehow managed to get it working to a certain degree, and it took us, what, forty-six years to do it?
This guy killed children in a camp that was run by the ruling Labour Party. He felt that the Labour Party has failed the country on immigration laws, probably by being too relaxed in his opinion. He can't target the current party members because they are too well-guarded, so he decides to get what he thinks are their successors: the children in that camp. Get them young, and you'll have them for life, see?