While you have to be mad to do what he did, I do think there are a lot of people who feel we in Europe are "under attack".
In the last few years we have had terrorist bombs in the UK and other European cities, we have had terrorist attacks on planes thwarted by the secret service, we have had "hate preachers" on our streets saying how they want to kill the Queen, our prime Minister, policemen etc.
We have people distributing "hate" anti-West material, selling "hate" anti-West videos and so on.
We have already had a situation in Italy with Italian people attacking Roma gypsy camps and setting fire to tents. The Italian government have been "busing" people back to Romania and so on.
You could see a situation in 10 or 20 years time where there could be a "civil war" in a European country between the indiginous population and some of the immigrant population.
Here is what happened in Italy in 2008
http://news.bbc.co.uk/1/hi/7400460.stm