For Lutherans, the idea of “buying one’s forgiveness” seems contrary to our view of a God of grace, but 16th Century Roman Catholicism made provision for this. Penance was a way of obtaining forgiveness for mortal sins.
“Medieval theology defined a mortal sin as a grave act of commission or omission involving willful disregard for God’s clear commands. [Venial sins, which involved minor infractions, ignorance of the consequences, or lack of intention, were forgiven anytime one prayed the Fifth Petition of the Lord’s Prayer.] Such a sin put a person in a state of mortal sin (that is, dead to God and liable to punishment in hell) and included two consequences: guilt and punishment. … The sacrament of penance consisted of three parts: contrition, confession, and satisfaction. While baptism contained stronger grace and remitted the guilt and punishment for all sin, it could only be performed once. As a result, the sacrament of penance, to which one had continual access because it was repeatable, became in the Middle Ages the crucial means of moving the sinner from a state of sin into a state of grace.” (The Roots of Reform, pp.13-14)
“Indulgences came into play precisely in this third part of the sacrament of penance, in that the church could be ‘indulgent’ and reduce or eliminate the temporal penalty demanded for particular mortal sins far beyond the value of an individual work. … There were basically two kinds of indulgences, both under the ultimate authority of the pope as Peter’s successor (based on Matt. 16:19), who granted to local bishops authority over the first kind. This kind was a partial indulgence, wherein the church lessened by a fixed amount the temporal penalty for sin for anyone who performed a certain act of piety. The viewing of relics… making a pilgrimage to a saint’s shrine, being in attendance at the annual celebration of a church’s dedication, and many other activities had indulgences attached to them.
The other kind of indulgence was a full, or plenary indulgence, attached especially to the apostles’ and their holy sites, and offering the remission of all one’s temporal punishment for all sins committed up until the time the indulgence was received.” (ibid, pp.15-16)
In the 11th statement (see below), Luther is referring to the parable of the wheat and tares (sown by the evil one while the owner slept) from Matt. 13:25. Through the Theses, Luther distinguished between canonical (ecclesiastical) penalties and penalties imposed by God during life and in purgatory. (ibid, from footnote on p.36)
1. When our Lord and Master Jesus Christ said, “Repent” (Mt 4:17), he willed the entire life of believers to be one of repentance.
2. This word cannot be understood as referring to the sacrament of penance, that is, confession and satisfaction, as administered by the clergy.
3. Yet it does not mean solely inner repentance; such inner repentance is worthless unless it produces various outward mortification of the flesh.
4. The penalty of sin remains as long as the hatred of self (that is, true inner repentance), namely till our entrance into the kingdom of heaven.
5. The pope neither desires nor is able to remit any penalties except those imposed by his own authority or that of the canons.
6. The pope cannot remit any guilt, except by declaring and showing that it has been remitted by God; or, to be sure, by remitting guilt in cases reserved to his judgment. If his right to grant remission in these cases were disregarded, the guilt would certainly remain unforgiven.
7. God remits guilt to no one unless at the same time he humbles him in all things and makes him submissive to the vicar, the priest.
8. The penitential canons are imposed only on the living, and, according to the canons themselves, nothing should be imposed on the dying.
9. Therefore the Holy Spirit through the pope is kind to us insofar as the pope in his decrees always makes exception of the article of death and of necessity.
10. Those priests act ignorantly and wickedly who, in the case of the dying, reserve canonical penalties for purgatory.
11. Those “tares” about changing the canonical penalty into the penalty of purgatory certainly seem to have been “sown” while the bishops “were sleeping.”
12. In former times canonical penalties were imposed, not after, but before absolution, as tests of true contrition.