Answer
After the separation of the Eastern and Western churches in 1054, the holding of councils by the pope became a way to give guidance to the church, both locally and ecumenically (for the entire church), on varying ecclesiastical matters. One of the most significant of these was the Council of Trent, held in the mid-1500s, which considered such weighty matters as the Lutheran Protestant Reformation and how to counter it, disciplinary reforms in the church, the definition of dogma, and ways to establish key tenets of Roman Catholicism. In fact, the growing complexities of the issues at stake grew so voluminous that it took 18 years, spanning the reigns of five popes, for the Council of Trent to actually convene.
During the Council of Trent, both Scripture and tradition were declared authoritative for the Roman Catholic Church, with tradition just as authoritative as Scripture. Salvation by grace alone through faith alone, one of the Reformers’ rallying cries, was rejected in favor of sacramental grace and a righteousness based on an admixture of grace and works.
There are seven sacraments instituted by Christ, according to the Council of Trent: baptism, confirmation, communion, penance, unction, orders, and marriage. The council condemned anyone who said the sacraments were not necessary for salvation or that man can be justified through faith alone without any sacrament. For all the talk in Catholicism of “grace,” the Council of Trent’s attack of justification by faith alone results in a theology of works-based righteousness; on some level, sinners must “earn” grace, or the sacraments would be unnecessary.
The council also confirmed the belief in transubstantiation, that the substance of bread and wine given during communion (the “Eucharist”) is changed into the actual body and blood of Christ, while the appearance of bread and wine remains.
Trent attendees stressed man’s incapacity to save himself, yet confirmed the necessity for the cooperation of his free will, including his resolve to receive baptism and begin a new life. They denied that predestination to salvation can be known with certainty (one rebuttal to this belief is found in Romans 8:28-30). Modern Roman Catholicism, in general, continues to hold to the beliefs put forward and accepted at Trent.
