Today, some 500 years after he lived, Martin Luther is regularly considered by historians to be one of the most important figures of the last millennium. Lifemagazine, for instance, in its survey of the most important people and events of the last thousand years, listed Luther third, behind only Thomas Edison and Christopher Columbus. The Protestant Reformation, sparked by Luther's actions, was ranked by Lifeas the third-most-important event of the millennium. He is regularly studied by high school students in their history classes. He is the subject of countless books, and even of popular movies. Few would contest the fact that he is one of the most significant figures in European history.

However, few people in the late fifteenth century—the time of Luther's birth—would have expected young Martin to achieve anything near this kind of greatness. Luther himself, near the end of his career, looked back on his life and explained how his fame had taken him by surprise:

The baby boy born to Hans and Margaret Luther on a rainy November evening in 1483 certainly did not seem like a potential world leader. He was from a peasant family of modest income. He had no influential connections in imperial or local politics. He lived in the small town of Eisleben, in a relatively unimportant corner of eastern Germany. Nevertheless, Luther would come to be one of the most important religious thinkers of all time, and his actions and ideas would deeply influence the future of Europe and the world. This is the story of how this apparently insignificant baby became a world-changing figure. In order to understand Luther's journey, however, we must begin a bit before his birth and examine the world into which he was born.