In the early 1500's in Europe, there was only one way to be a Christian. Martin Luther was a monk who lived in a monastery in Germany.  The more he prayed and studied the Bible, the more doubts he had about some of the things the church was doing. 

A man named Tetzel came to town and made the people very excited.  He told them that the Pope had given him some special tickets to heaven, called indulgences. Poor people used their savings, their grocery money, and even sold their most important possessions so they could buy tickets to heaven for themselves and the people they loved, even if they had already died. This made Martin Luther very angry.  He wrote a list of 95 reasons why selling tickets to heaven was wrong and wouldn't work.  There weren't any newspapers, television or the Internet in those days.  To make his views known, he nailed them to the door of the church in Wittenberg, Germany on October 31, 1517. 

In his 95 theses (or reasons) Luther said the Bible taught that forgiveness is a gift from God.  The church isn't a store where we can buy or earn eternal life. Only God knows what is in our hearts and if our faith is true. Eternal life is a matter of faith, not what we say and do, and decisions about it belong to God, not the church. Luther thought that selling tickets to heaven was the church being greedy and taking advantage of people with sincere faith in God.  The church was making a terrible mistake.

 His courage in placing the 95 Theses on the door of Wittenberg Church set the Reformation in motion. Luther went on to expand his criticisms of church practice and was one of the great leaders of this important movement.

The leaders of the church didn't like being criticized. Eventually they told Luther if he didn't believe in God according to their rules, he would be kicked out of their church for good (excommunicated). According to church rules, being excommunicated meant you couldn't go to heaven. Luther knew the church couldn't decide whether or not anyone went to heaven, so he remained true to God and his faith. 

Martin Luther didn't want to create a new religion, he just wanted to fix (or reform) the mistakes being made by the people running the church.  They didn't want to change, so Luther's ideas became a separate religion.  Those of us whose faith is based on his vision of the relationship between God and people are called Lutherans.