The Gutenberg Press, created in 1439, was the first ever movable type printing press. Before this time, books were scarce due to the fact that they had to be rewritten. With the creation of movable type, books could now be produced on a mass scale.
Due to this technological development, information regarding the Reformation could reach a larger audience. Now members of the Reformation could expose the corruption of the church to thousands of people at a time.