Organized religion is a dangerous plague on humanity, the Abrahamic religions being the most dangerous.
Head over to Norwegianity and read Mark Gisleson's excellent post. A snip or two:
Nine million people died because of evil and corrupt Popes. Bear in mind that at most there were only 350 million people in the world at that time. The Crusades killed two percent of all the people in the world. By comparison, you have to credit Hitler with ALL WWII fatalities (Europe AND Asia), to match that horrific toll. Let me repeat that: percentage-wise, the Crusades killed as many people as WWII did.Be sure and go read the rest.
On the other hand, I'm not a huge fan of Islam. On a personal level I find most manifestations of Islam to be as profoundly retarded as your typical Christian sect. Those who live their lives by truly Christian or Islamic teachings are, however, superior examples of homo sapiens. But since we're talking about no more than a few thousand people worldwide, we're really talking about anthropological curiosities more than any kind of coherent religious movement.