The printing press was invented in 1440, allowing written works — like the Bible — to be widely produced and distributed.
Desiderius Erasmus’ Greek New Testament of the Bible, the first of its kind to be made, was published in 1516, facilitating the movement “ad fontes,” and a close examination of scripture in its original language.
The Protestant Reformation kicked off contemporaneously, circa 1517.
Coincidence? I think not.
When the Word of God is unleashed, expect theological reform.
At the heart of the Reformers’ agenda was to put the scriptures into the hands and ears of the people. Contrast that with the Roman Catholic Church, who, at the time, forbid preaching or translating the Bible into the common language. (Of what were they afraid?)
The Reformation was a movement of the scriptures.