And the results of the first 13 years of Muhammad's career as a prophet seem to bear this out. He only gained 150 followers by just reciting the verses of the Koran. It's possible that only very uneducated, naive people fell for it. That is, until he switched to violence.
But I see real brilliance in the ideology taken all together (the Koran, Hadith and Sira — the Islamic trilogy). Sinister, yes. But ingenious in its own way. You can read more about that here: The Terrifying Brilliance of Islam. Yesterday, as I looked at a Muslim I work with, a cold sensation ran through me when I realized he has 15 children, and in every way appears to be a nice man, and a hard worker. But because of Islam's tenets, he can live his whole life being nothing more than a kindly, industrious fellow, never raising any suspicion and never doing anything that should justify suspicion, and yet raise his kids as devout Muslims, which means they would believe in the Koran and the "sacred" example of Muhammad, which would mean, if they ever read the Islamic trilogy when they grow up, they will discover that they are obligated to wage jihad against the non-Muslim world until everyone on earth has been subjugated under Islamic rule. And if they don't commit themselves to this cause, they will spend eternity being tortured in horrifying ways.
And when a country establishes Islamic rule, the nature of Islamic law will slowly and relentlessly wear down resistance in anyone who hasn't already converted to Islam. It may take centuries, but the result is inevitable: Almost everyone in the country will eventually become a Muslim, and the previous culture will have been completely erased.
It's like a pernicious but very patient virus.
But we don't need to take it lying down. We're certainly not helpless. We can treat it like we would any other virus: Contain it, stop it from spreading, inoculate everyone against it, and if possible, eliminate it completely. We can start here: What's the Game Plan?
This was also posted on Inquiry Into Islam and Foundation for Coexistence so you can more comfortably share it with certain people.