Job, a “blameless and upright man” (Jb 1:1) used to offer sacrifices regularly to the Lord for each of his sons (see Jb 1:5). In this way he hoped to offer his own sacrificial acts on their behalf, trusting that God would credit his good deeds to their benefit. A similar intention is involved the Catholic practice of indulgences.
The life of each person who is in Christ — whether on earth, in purgatory, or in heaven — is joined together through him with the lives of all the others, forming a supernatural unity, the “body [of Christ] …. If [one] part suffers, all the parts suffer with it; if one part is honored, all the parts share its joy” (1 Cor 12:12, 26).
A Christian who seeks to be purified of sin by God’s grace is thus not alone. The holiness of other believers — their merits, which have value because of their union with Christ’s merits — can profit him spiritually. The spiritual goods of this “communion of saints,” as the Church calls it, is a treasury that includes the infinite merits of Christ himself, as well as the prayers, sacrifices, and other good works of our Lady and all of the saints.
When Catholics obtain an indulgence, the Church, through the power of “binding and loosing” sins that Christ has given her (see Mt 18:18; Jn 20:23), intervenes on behalf of individual Christians, opening for them this treasury of merits. What exactly does an indulgence accomplish? It is “a remission before God of the temporal punishment due to sins whose guilt has already been forgiven” (Paul VI, apostolic constitution, Indulgentiarum doctrina, Norm 1) (Catechism 1471).
Sin has a double consequence: damage to our relationship with God (guilt), and damage to the order he has established. Through the sacraments of Baptism and Reconciliation, we receive forgiveness in Christ, a healing of our relationship with God that takes away our guilt. Nevertheless, every sin also involves a disordered love that spiritually and morally disfigures us and the world around us, leading to temporal punishment.
Even after we receive God’s forgiveness, this second kind of damage must be repaired through acts of penance and charity. Scriptural examples of this reality abound: For example, God forgave David his sin of adultery with Bathsheba, but the king still had to endure penitentially the chastising consequences of his son’s death (see 2 Sm 12:13-14). Indulgences can assist Christians in this reparative process, which is called “satisfaction.” (See also “Where Is Penance Found in the Bible?”)
Related Scripture:
Texts Cited: 2 Sm 12:13-14 • Jb 1 :1,5 • Mt 18:18 • Jn 20:23 • 1 Cor 12:12, 26
General: Gn 3:16-19 • Ex 32:30 • Dt 32:48-52 • Mt 16:19, 24 • 2 Cor 1:5-7; 2:5 • Phil 3:10 • Col 1:24
Catechism of the Catholic Church: 1471-1479 • 1498