After Martin Luther, a Catholic priest, nailed his Ninety-Five Theses on the door of the Wittenberg Church in 1517, there was growing dissent among priests and princes alike. Therefore, concerned leaders of the Catholic Church met in Trent in 1545 in order to establish firmly the Church's stand on certain issues and specifically to refute the beliefs of Luther and other Protestants. In short, this Council met in reply to the Protestant Reformation.
The following differences were clarified relating to Martin Luther:
1. Luther contended that the Bible is the main religious authority.
The Council of Trent refuted this by contending that religious authority extends to faith and tradition as well as scripture.
2. Luther argued that the Church should have no power over the absolution of sin, specifically with the selling of indulgences.
The Council refuted Luther's argument against indulgences by putting forth a Decree Concerning Indulgences stating that the power to grant forgiveness of sins was given to the Church by Christ. It also decreed that anyone who does not believe in this power will be condemned as a heretic. (This decree was specifically directed at Luther.)