Print, reform, and reformation.

During the reformation, there were two major developments. They were the printing press and the use of the vernacular. These developments were crucial to the history of literacy, but they were not immediately recognized.

As per Harvey J. Graff, "Neither Luther and his theses, the church's hierarchy, the social context, the
printing press nor any single factor or development caused the events that
perminatly spit the world of western Christendom and firmly ended the middle
ages."

Although the printing press did not determine the reformation, it prepared for the coming of the reformation. It played a major role in the church, for it allowed holy writings to be published in a mass form, and it allowed notices to be posted on church walls, doors, and gateways, for people to read with much interest. Luther's own works were also in high demand. http://en.wikipedia.org/wiki/Printing_press