people who seek a religion are usually uncomfortable with living in uncertainty, and thus the more direction a religion provides (the less that is left up to personal choice) the more desirable the religion appears to those who seek to eliminate uncertainty from their life. thus islam, a religion which offers its adherents strict guidelines for most every facet of their behavior, is a religion that has great appeal to those who seek religion.
afterall, when muhammad started the religion he said the reason was because the tenants of christianity were far too lax. simply loving everyone and everything isnt enough, said muhammad. a person also needed to follow a bunch of strict laws that govern everything from the food you eat, the way you dress, to the manner in which you pray, and so on.
its really just a bunch of bullshit. and the fact the guy led armies in battle should be plenty to convince anyone with a decent capacity for reason that he was in no way a holy man.