For decades some humanists as well as members of the clergy tried to alert the papacy that certain changes were needed. Not only men like Erasmus, Luther or even Wycliff and Hus tried to make changes, but also clergy like Cardinal Ximenes de Cisneros (1436-1517) and Bishop Gian Matteo Giberti (1495-1543). The Catholic Church noticed that it started slowly to lose ground in Northern Europe. People and royalty joined the Protestant side. Although the Church did point out Luther's theological errors at the Diet of Worms, nothing much else happened.
That is until Pope Paul III started the Council of Trent on 13 December 1545. In response to the growing uprising of Protestantism and the Reformation, the Catholic Church responded by having the 19th ecumenical council. The Council lasted till 1563, and was held in three periods with a total of 25 sessions. The Council was held as a reply to the challenges posed by the Reformation, to define Catholic doctrine and concluded with various decrees were issued covering every aspect of the Church authority. The Council of Trent clarified many issues about which there had been continuing ambiguity throughout the early church and the Middle Ages, including the precise number and nature of the sacraments, the veneration of saints and relics, purgatory, the authority of the pope, and the use of indulgences. The “either/or” doctrines of the Protestant reformers—justification by faith alone, the authority of Scripture alone—were rejected in favour of a “both/and” doctrine of justification by both faith and works on the basis of the authority of both Scripture and tradition. Additionally, the Latin Editio Vulgata Bible was reaffirmed against Protestant insistence upon the original Hebrew and Greek texts of Scripture.
Another important factor during the counter-reformation is the setup or founding of the Society of Jesus. Through education, by setting up colleges, universities as well as missionary work around the world, they hoped to spread the teachings of the Church. Not only to teach the clergy but also commoners.
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