Follow me and I will make you fishers of men, Jesus said. Here van de Venne's painting Fishing for souls. Protestants on the left and Catholics on the right.
Now as to the popes of Rome, who pretend themselves Christ's vicars, if they would but imitate his exemplary life.
Erasmus of Rotterdam
Many in the latter part of the Middle Ages opposed the papacy with its flamboyant life and patent interpretation of the Word of God. In fact, it is entirely out of the question that Jesus appointed Peter to be the first Pope, gave him the keys to the Kingdom of Heaven, and declared him the rock upon which the Church would be built.
..the Church of God is only the sum of the souls he created which IS the corporate body of Christ..
..Here stands your brother with the key to Heaven in his hand, held out to you. Let not the dream of specialness remain between you..
Jesus in A Course In Miracles
Not all protestors agreed on everything, but agreed that the Roman Catholic Church had deviated from the Bible (which began to spread after the invention of the printing press) and had become an authoritarian hierarchy that was not compatible with the teachings of Jesus.