The Protestant Reformation in the 15th century was devastating for the catholic church because it broke its exclusive hold over Christendom and ended up leading to the diverse branches of today. Due to the overspending on monuments, selling of indulgences, and the promoting of family members to valuable offices, the church made itself vulnerable to criticisms. Martin Luther and his 95 theses, referred to as the Disposition on the Power of Indulgences, brought these actions to light and eventually led to the schism that changed Europe. The Renaissance Popes saw this as a challenge to their authority. At any other time, Luther would have just been labeled a heretic and executed. However, one thing allowed him to become immortalized in the minds of the public: Johaness Gutenberg and The printing press.
The press introduced the era of mass media and communication which changed the power structure of Europe. It broke the hold that the aristocracy had over literacy, allowing the poorer dregs of society access to education and creating the middle class.The relatively unrestricted circulation of information and (revolutionary) ideas transcended borders, captured the masses in the Reformation and threatened the power of political and religious authorities. The invention of the printing press removed control of written material from the Catholic Church and made it difficult for the church to inhibit the spread of what it regarded as heretical ideas.
I am the Anti-Doctor, a timelord that has traveled back in time to the 14th century. I have chosen the beginning of the Renaissance era to warn the Pope of the schism and alter the timeline. Eliminating Guttenberg would not stop the reformation, as someone else will simply come along to invent the printing press sooner or later. For the corrupt church to continue its decadence in peace, the influence of the printing press must be curtailed and prevented from spreading. What measures should the catholic church take to ensure this?