Who is responsible for the decadence of Muslims?

Who is responsible for the decadence of Muslims? Medium:Books Edition:ORIENTAL WISDOM:

Whether through assertive and frank speeches, or unspoken accusations, Islam is often implicated in the overwhelming situation in which many Muslim peoples find themselves. The major axis of this accusation is invariably the alleged incompatibility of this religion with the modern world, or at least, the brake it opposes to evolution. Far from denying the usefulness of the progress of science or questioning established knowledge, and far nevertheless from calling for the dissolution of Islam by conforming to the Western model, the author invites all Muslims to seek first in itself what founds the spirit of Islam. On this foundation must be built the union, which allows man to fulfill his primary function: to guarantee the prosperity of life on earth. But what are these foundations without which the edifice crumbles and leads civilization to decadence? It is these essential subjects that the author addresses here.