Thursday, we’re talking about Martin Luther. In the 16th century, he ignited a movement to rethink the traditions and beliefs of Christianity. He came to be seen as a heretic or revolutionary, but the historian Craig Harline said Luther never set out to be either of those things. He began as a cranky friar who obsessed about the fate of his soul. He went looking for answers, and when he found them, refused to keep his mouth shut. Harline has just written a new book called A World Ablaze.