Today we would cry foul if someone was presumed guilty before given a trial. The issue was not so much the sale of Indulgences as charged, as much as what an individual Dominican Friar was doing which was contrary to what the Catholic Church taught and teaches about Indulgences.
Johann Tetzel (1465 ‚Äì 11 August 1519) was a German Dominican preacher remembered for selling indulgences and for a couplet attributed to him, “As soon as a coin in the coffer rings / the soul from purgatory springs.” His error for which among other things he was found by the Catholic Church to be in error about was he promoted contributions for the rebuilding of St. Peter’s by promising something the Church does not. He promoted the error that if one gained an indulgence, (either through charitable giving, prayers, acts of mortifications etc.) those indulgences could be “saved up” and used against future sins one had yet to commit. In other words he was selling licenses to sin. Luther also charged that Tetzel taught that one did not need to have contrition or sorrow for ones sins, nor do they have to confess their sins, or seek God’s forgiveness.
The Catholic Church has never held nor promoted what Tetzel was attempting to do. It was not sanctioned, and there is evidence that the charges against Tetzel by Luther and other Protestant writers where trumped up, and not what he really taught. It is possible that Tetzel who died a rejected man, is one of the most misrepresented and slandered person in history, aside from our Lord himself. But then only God knows the disposition of his soul.
Indulgences can be gained through acts of charity, (Corporal works of Mercy) Prayers, participating in a pilgrimage, or other acts. However the conditions are that you must be in a state of grace, ie. if you are in a state of mortal sin, you must confess your sins prior to the acts you preform in order to gain the indulgence, and some indulgences require that you receive communion and offer prayers for the Pope.
Indulgences used to be classified by periods of time, ie, days, quarentines (40 days) Years, or Perpetual. They are based on the penances that where imposed by the Apostles and the priests and bishops in the early Church. In Apostolic and early Church times there was no privacy in confession, one came forward to the Apostles or the bishops who the Apostles appointed, and knelt confessing their sins in front of the entire community. (See Saphorah and Ananias in the Acts of the Apostles) after the confession the penance was imposed and the absolution given. Compaired to today the penances where very harsh. One could be barred from receiving communion until ones deathbed, or one could be instructed to not eat meat for a day, quarentine, year etc. This punishment, or penance imposed by the Apostle or bishop is the basis for the indulgence. Indulgences where means of substituing some act, (as above) that sould suffice for the penalties described above. Protestants tend to still teach that indulgences are licenses to sin, and that Catholics can go to confession and not be sorry for their sins, and still be forgiven. Both ideas are contrary to what the Catholic Church teaches.