holyoffice has a brilliant list of summaries defining key terms in Christianity. Consider, for example, this definition:
The Protestant Reformation
This is the name historians give to a major labor dispute that erupted in Germany in 1517 when a group of monks hammered a proposed union contract to the door of the pope's house, requesting a 95 percent pay raise. The pope refused to negotiate with the monks union until it agreed to pay to have the door fixed, and the result was the world's longest-running strike. For nearly 500 years, a huge portion of Christians have been on strike from being Catholic, saying they are "justified" in their work stoppage because the pope won't expand the number of indulgences they get per year. Currently, the matter is in arbitration.