Risen From History's Crypt

Islam was moribund and in retreat at the end of the 19th century. Then came two things that, I hesitate to call it Divine Intervention but perhaps some other agent was at work, rescued it. 

The first was the shift to oil powered naval vessels. The change from sail to coal fired steam had already occurred but the Royal Navy's shift from coal to oil made control of the Middle-East oil fields critical to the British. The Arabs and Iranians shifted from despised or picturesque natives of interest only to Missionaries, Romanticists, Archeologists, and various cranks to potential partners and valued assets to be cultivated. 

Next came the rise of Marxism as a challenge to the core ideologies of the West. Those being Judeo-Christianity, Aristotelian rationalism and inquiry, Empiricism and the Scientific Method in a tradition championed by Francis Bacon, limited government and individual liberty under the rule of law, and Capitalism. The West was weakened internally as both large swaths of the masses and of the elites fell away from support for culture and the institutions, which themselves became corrupted, that were always more important in expanding the sphere of Western dominance than the military power which was among their end products. Islam was itself energized as it adopted the rhetorical and organizational tools that Marxism provided for its revival.