In a column in the Jerusalem Post, intriguingly titled "A General Theory of Just About Everything," Jonathan Rosenblum tackles those questions. I will not try to summarize his thesis here; read the column. However, I just have to quote these priceless lines:
Contemplating the jihadists' logic - the logic of those who crave death - is terrifying and causes many to deny the obvious: the West is in a religious war. After Canadian police uncovered a plot to blow up the Parliament buildings and behead the prime minister, the police spokesman described the plotters as coming from a broad cross-section of society - albeit all named Muhammad or Ahmed. And the deputy commissioner of Scotland Yard called those plotting to blow up 10 airliners nothing but common criminals, at most "hiding behind certain faiths."