"Dehumanise" the enemy, and you start to underestimate them, and that is always a mstake. "Dehumanise" the people who aren't the enemy to start with, and you turn them into the enemy.

The murder of this young man was a calculated action intended to achieve certain effects. Quite what these effects are intended to be is uncertain.

Getting people to see this group as a major player in the confusing war going on in Iraq would presumably have been one of them. Another is surely to ensure that the Americans will respond in a way that makes more people in Iraq resent their presence, and see anybody whomis fighting them as on their side. (Which in fact is very unlikely to be the case, especially when it comes to the kind of people who killed Nicholas Berg.)