By the year 1000, Christianity had survived a millennium of constant threat and emerged as virtually the only faith in Western Europe. Christianity stood on the verge of a new era. Nonetheless, its greatest challenges were before it. Western Europe was wracked by the constant warfare of its own nobility. Relations with the powerful and cultured Eastern Orthodox Church were marked more by rancor than fraternity. To the south was the greatest threat of all -- the Muslims. At the height of their culture, the Muslims possessed the learning, strength and prowess to drive straight through the heart of Europe. However, Western Christianity overcame all of these challenges and became a driving force, leading Europe from the depths of the Dark Ages to unprecedented power and prestige. Christianity harnessed the aggression of the nobles for the Crusades, and drove the Muslims out of Europe for the first time in nearly a thousand years.
By the year 1500, the Church was at its zenith around the world, with its power concentrated in the Pope. Then a lowly friar, Martin Luther, in a small German town ignited a revolution that shattered the Church, tore Christendom apart and reinvented it from within. The Protestant Reformation heralded the end of the medieval world and the beginning of the modern age. Protestant efforts led to the rise of science, industry and the modern nation. For the first time in the history of the West, church and state had been separated. Again, Christianity reinvented its role in the modern world.