Queue up people claiming that he was just f**** in the head, not Christian
First cab off the rank. Anders Breivik did not identify himself as a Christian in the sense that he was a follower of Christ but merely a 'cultural Christian'. His motivation was to protect 'Christian Europe', not to protect Christianity or Jesus. In fact he was quite scathing of religion in general saying "Religion is a crutch for many weak people and many embrace religion for self serving reasons as a source for drawing mental strength". 
It's still too early to say for sure, but I'd be willing to bet that the guys who carried out the recent attacks in France are doing so because they believed it is the 'will of Allah', the prophet 'commands it' etc etc.
A second important distinction is that Anders Breivik, even if he wanted to, could not justify his actions based on what Jesus or his disciples taught. Islamic extremists can and do quote directly from the words of Mohammad to justified their violent actions.