Answer:
It significantly reduced the Catholic Church's political power. Before the reformation, the pope had authority over even European governments. This power started to decay as Christian populations split into Catholic and other denominations. As a result, the population of European Catholics dropped, as some people adopted Martin Luther's doctrine. Further, common folk started reading the Bible for themselves, thanks to Luther's translation of the Bible into German, a language that many people understood; this is significant because people no longer needed to rely on a priest to interpret the scriptures from Latin-- people could look in the Bible for themselves, in their own language.
HTH :)