The pen is mightier than the sword, the old saying goes. The challenge presented by radical Islamic extremism to the civilized world is one that cannot be defeated solely by military means; it is the nature of such radicalism to metastasize and grow when it is physically attacked.

This is because extremism of this sort is based on the belief that Islam is besieged and persecuted by armies of infidels and it is the duty of “true” Muslims to kill in its defense. The fact that the shocking attacks in Brussels last month came just days after the arrest of one of the planners of the recent Paris attacks demonstrates this martyr effect.

Swedes shouldn’t overlook the significance that one of the suspects in the attacks became radicalized in Malmö. Why were ideas grounded in hate and violence more attractive than the tolerance and understanding typically associated with Swedish values?

One source of strength and strategic advantage among these radicals is in their belief that terrorism is sanctioned by God. This is the great “mirage” of extremism and no amount of military hardware can defeat it.

Rather, extremism must die in the battlefield of ideas.