In the 1400s the first printing press was invented by Johann Gutenberg, and it would change the intellectual landscape of Europe forever.
In 1476, Englishman William Caxton built his own, and popular books and pamphlets began to circulate. Early pamphlets by Christian humanists such as Erasmus began to criticise the church tentatively. The push for reform began to build. A wave of protestant writers joined humanists critics.
By the 1500s, printing was well established. In Germany, Martin Luther, a Doctor of the Church and a charismatic speaker, wrote many tracts about the corruption of the church. 
He demonstrated how that common Catholic practices and institutions had no basis in scripture, especially the sale of indulgences which funded elaborate building projects in Rome, including St Peter's Basilica. 
Many other thinkers would follow his lead, including John Calvin, and Ulrich Zwingli, and William Tyndale in England.
Widespread pamphleteering from Humanists and Lutherans changed opinions on the ground across Europe. By the time Henry VIII was on the throne, criticism of the church was starting to grow. The Invention of the Printing Press spread ideas that challenged the Catholic Church.