I've always known that Islam and the Church of the Latter Day Saints share many similarities (white robes in the Temple and on the Hajj are only one), but it was only while watching the PBS special The Mormons that I realized the famous founders of these religions are two sides of the same coin.
There are thousands of military, political, and religious leaders strewn thoughout the pages of human history, but relatively few of them understood some basic elements of human nature that are easily susceptible to exploitation as well as Moe and Joe. To really gain the allegiance of your followers, you must persuade them that you are a Prophet as well as a King. An early and famous example of this, known to both Smith and Muhammad, was the Jewish King David. The Hebrew Scriptures record that he was anointed and accepted as Prophet years before he was crowned as King. David claimed in II Samuel 23:2 that "The Spirit of the Lord spoke through me", and both Muhammad and Smith later claimed similar access to revelations from God. Any leader with political, military, or economic ambitions who can persuade his followers that he hears and communicates the very words of God can easily gain tremendous control over them. Joseph Smith and Muhammad were both examples second to none.
Closely related to this is the ability to promise your followers the bliss of eternal life in return for their faithful obedience. Muhammad with his virgins that awaited martyrs, and Smith with his visions of celestial families where disciples would be reunited forever, both mastered this. There is no greater motivation to entice followers than the promise that they will enjoy the rewards of their obedience throughout all eternity. People sometimes question why both Nazism and Communism, both such powerful forces in the last century, lost so much influence in so short a time. It's one thing to persuade followers they will be able to share the produce of a collective farm; it's quite another thing to convince them that millions of years from now they will still be blissfully enjoying the fruits of their allegiance.
Muhammad and Joseph Smith also understood that people like regimented lives, and want to be told what to do. Both religions organize behavior with lists of things that are allowed and prohibited, structure for family and social relationships, rewards for obedience and public displeasure for disobedience.
Each of the founders realized the significance of convincing their followers that they are somehow better, more correct, than everyone else. In the Quran the distinction is between the believers, who are the best of people, and all others who collectively are the worst of people. In Mormonism, it is the belief that only their church is free from error; only they have been restored to the truth.
Perhaps most important of all, both men understood the importance of controlling their followers. Leaders are not to be questioned, sacred texts are not to be critically examined, dissent is not tolerated, and history is only to be understood through the prism of its adherents.
Incidentally and in conclusion, both religions like to talk about how fast they are growing, but neither likes to publicize stories of people who leave. For each of them, (and I would say this is a good thing) that list is rapidly growing.