Radical Islam is nothing but a political tool to rise to power. Find exception, exploit it, conquer it.
As far as recruiting and those that tolerate a Islamic theocracy, lets look at it from a psychological point of view:
Its pretty damned easy to brain wash masses. Take a group (or country-full for that matter) of predominently poor people, brain wash them with fanatical religion, threaten them by taking away the blocks of Maslow pyramidical heirarchy, and voila! You have true believers ready to cash in so they can meet their virgins.
Works in any religion really...just need the right ingredients...poverty, fundamental religion, a threat...and an enemy of those people to focus their anger on.
Not all are impoverished, an example would be Atta, the head guy of the 9/11 attacks, and a few others in that cell were not exactly impoverished, but my statement above stands for a majority of radical fundumentalists. There are always exceptions. There are young people who are searching for a "cause", or searching for the reason they exist on Earth....I had a psych teach that once stated "people believe they're on earth for a purpose at some point in their lives, whether it be saving whales, having babies, or blowing themselves up..." That was 20 years ago...