In reality, scholars debate whether Luther nailed anything to a door. What we do know is that in 1517 he wrote a letter to his religious leaders that included his 95 theses, which quickly spread across Europe in pamphlet form.
It was printed pamphlets like this that really got the Protestant Reformation rolling. And Luther was at the center of it all. In fact, according to the biographer Lyndal Roper, Luther was responsible for20 percent of everything printed in Germany between 1500 and 1530.
Because of the printing press, far more people read for themselves what was in the Bible.