Less than 50 years after Muhammad's death, Islam had spread to become a world empire stretching from Spain to India...This advanced civilization had no rival for hundreds of years...until....something happened. Starting about 1500,a general decline set in, and Islam has never recovered....the Mullahs wondered why this had happened, and the answer they came up with was- the believing community was not strict enough, there has been a falling away, a loosening of morals....So the clerics in Saudi Arabia concocted fundamentalist Wahabism in the mid 1700's.....
This eventually led to the publication of 'Milestones', by the radical Qutb, who was executed by Nasser in 1966. Jihadists everywhere fervently read and believe this tract, which indicts the West for its primitive decadence, and offers Sharia(Islamic Law) as the solution the the worlds problems.