Here's John Quincy Adams observing that jihad progresses not only by violence, but also by fraud -- by preaching, demographics, economics, and the subversion of non-Muslim societal institutions from within (jihad by stealth).
". . . he [Muhammad] declared undistinguishing and exterminating war, as a part of his religion, against all the rest of mankind…The precept of the Koran is, perpetual war against all who deny, that Mahomet is the prophet of God…the faithful follower of the prophet may submit to the imperious necessities of defeat: but the command to propagate the Moslem creed by the sword is always obligatory, when it can be made effective. The commands of the prophet may be performed alike, by fraud, or by force."Following is General George S. Patton, Jr., on the retarding effects of Islam.
A few things to keep in mind: First, by "Arab" Patton clearly meant "Muslim," since many Arabs were Christian. Second, by 700 much of the West was Christian; to the degree that its people obeyed the commands of Christ, the West was already morally advanced. Finally, it's not just a lack of development, it's making "divine" the violation of Christ's commands that destroys human souls.
"One cannot but ponder the question: What if the Arabs had been Christians? To me it seems certain that the fatalistic teachings of Mohammed and the utter degradation of women is the outstanding cause for the arrested development of the Arab. He is exactly as he was around the year 700, while we have kept on developing. Here, I think, is a text for some eloquent sermon on the virtues of Christianity."
--from War As I Knew It, by General George S. Patton, Jr., 1947