The reopening of the Council of Trent marked a significant moment in the Catholic Church's response to the challenges posed by the Protestant Reformation. Convened by Pope Paul III initially in 1545, the council sought to address various doctrinal and practical issues within the Church. After a series of interruptions and changes in leadership, Pope Pius IV resumed the proceedings. His papacy, which began in 1559, emphasized the need for unity and reform within the Church to combat the growing influence of Protestant ideologies. The third session began on January 18, 1562, and was attended by a multitude of bishops and theologians who brought to the table a range of perspectives on the theological and administrative issues at hand.

During this session, participants deliberated on critical issues including the nature of sin, grace, and the sacraments. One of the distinguishing aspects of this session was the discussion surrounding the relationship between faith and works, which was a contentious topic, particularly in relation to Protestant beliefs. Furthermore, the council aimed to reform the clerical hierarchy and improve the education and moral standards of priests. The decisions made during this session would ultimately shape Catholic teachings and practices for centuries, as various decrees were issued that reaffirmed key doctrinal elements such as the importance of tradition alongside scripture, the necessity of clerical celibacy, and the validity of the seven sacraments.