First, those who sin are liable to punishment: "I will punish the world for its evil, and the wicked for their iniquity; I will put an end to the pride of the arrogant and lay low the haughtiness of the ruthless" (Is. 13:11). Second, punishments can be temporal and eternal. Hell is an eternal punishment. But we need only look at the story of Adam and Eve to see that punishments can also be temporal only, as when God told Eve that women would have painful childbirths, and Adam that he would encounter many difficulties in farming the land (Gen. 3:16-19; See also Gen. 4:9-12, Deut. 28:58-61, Is. 10:16). Third, even when sins are forgiven, temporal punishment remains. After David committed adultery, "Nathan answered David: ‘The Lord on his part has forgiven your sin; you shall not die. But since you have utterly spurned the Lord by this deed, the child born to you must surely die'" (2 Sam. 12:13-14). Moses was told, "Because you did not believe in me, to sanctify me in the eyes of the people of Israel, therefore you shall not bring this assembly into the land which I have given them'" (Num. 20:12; cf. 27:12-14). Even Christians who are forgiven die, which is one of the punishments given to men as a result of the Fall. Fourth, God blesses people as a reward to others. God promised to reward Abraham's descendants as a result of his faithfulness (Gen. 17:6-8). Jesus performed miracles due to the faith of others, as He did with the daughter of Jairus (Mark 9). Fifth, God also remits temporal punishments as a reward to others: "The Lord said to Solomon: 'Since . . . you have not kept my covenant . . . I will deprive you of the kingdom and give it to your servant. I will not do this during your lifetime, however, for the sake of your father David" (1 Kgs. 11:11-13). God promised Abraham He would spare Sodom on account of the righteous people there (Gen. 18:16-33). Sixth, the Church remits temporal penalties with the authority given it by God. Some sinners in Corinthia were assigned a penance by Paul: "I have already pronounced judgment in the name of the Lord Jesus on the man who has done such a thing. When you are assembled, and my spirit is present, with the power of our Lord Jesus, you are to deliver this man to Satan for the destruction of the flesh, that his spirit may be saved in the day of the Lord Jesus" (1 Cor 5:3-5). Later he granted an indulgence: "For such a one this punishment by the majority is enough; so you should rather turn to forgive and comfort him, or he may be overwhelmed by excessive sorrow. So I beg you to reaffirm your love for him . . . Any one whom you forgive, I also forgive...in the presence of Christ, to keep Satan from gaining the advantage over us; for we are not ignorant of his designs" (2 Cor 2:6-8, 10-11). Paul was not sure if the penance the Corinthian did was enough to expiate his sins, so he said, "if I have pardoned anything". Seventh, indulgences can be applied to the dead because the dead are blessed as a reward to the living: "They turned to prayer, beseeching that the sin which had been committed might be wholly blotted out" (2 Macc. 12:42). These men died "in godliness" (2 Macc. 12:45), so the prayer was for the remittance of temporal penalties.

Over the centuries, the saints have done penances in excess of what they needed to do in order to satisfy their sins. These merits, together with the infinite merits of Jesus Christ, which are actually superabundant and can satisfy for all sins, form the "treasury of merits", from which the Church grants indulgences to satisfy the temporal punishment due to sins already forgiven: "It was granted (the Bride) to be clothed with fine linen" (Rev. 19:8); "For the fine linen is the righteous deeds of the saints". The Jews also believe in what is called "the merits of the fathers", and believe that the Jews received certain promises because of the merits of their Jewish forefathers.

Before the Second Vatican Council, indulgences were assigned a certain number of days or years. An indulgence of 300 days did not mean 300 days off purgatory, however. Although it did not specify anything in particular, it was considered to be the equivalent of 300 days of penance as was done in the early Church. Now, indulgences are only labeled "partial" (which remits a portion of one's punishment" or "plenary" (which remits all of one's punishment). The Church had full authority to make this change (Matt. 18:18), but it is God who determines how efficacious these indulgences are.

Protestants argue that indulgences infringe on the sufficiency of Christ's death on the cross. But the blood of Christ saves us from eternal punishment, whereas indulgences pardons us from temporal penalties. Yet even these temporal penalties are remitted by Christ's death, because it is His merits that are in the treasury, and the merits of the saints that are in that treasury were all merits that were won as a result of Christ's death. So any way you look at it, Christ is responsible for the remittance of temporal punishment.