According to the Catechism, an indulgence,
"is a remission before God of the temporal punishment due to sins whose guilt has already
been forgiven, which the faithful Christian who is duly disposed gains under certain prescribed conditions through the action of the
Church. An indulgence is partial or plenary accordingly as it removes either part or all of the temporal punishment due to
sin." What does that actually mean? The Catechism goes on to explain more precisely this definition. In order to understand this, we need to remember that sin has a
Mortal sin breaks our relationship with God. It deprives us of communion with God and makes us incapable of
eternal life should we die in a state of mortal sin. That's why it's so important for us to go to confession whenever
we're in a state of mortal sin, which is far more often than many realize. When we're deprived of eternal life due to our own actions, this is called the
"eternal punishment" of sin.
doesn't break our relationship with God, but it does harm it.
Every sin, even the less-serious venial ones, carries an unhealthy attachment to something of this world.
That's why we commit sins: because we have an attachment to some aspect of that sin. These attachments to sin which we have must be purified before we may
enter heaven, as Revelation states that nothing unclean may enter heaven. This purification therefore needs to happen either on earth or
in purgatory should we not die in a state of mortal sin. The purification of our attachments to sin is called the
"temporal punishment" of sin.
When we go to confession,
we're purified of our eternal punishment of sin, since we confess our mortal sins and obtain absolution for
them. We're now restored to our relationship with God, and this can only be done through sacramental confession. However, there still
remains the temporal punishment because even though we've been absolved, we still tend to have those attachments to sin and thus
will most likely sin again. If we die in a state of grace, which is to say that
we're not in a state of mortal sin, then we're spared the eternal punishment of hell, but many still carry these attachments to sin and thus require the remission of the temporal punishment.
This is what purgatory entails, but the remission can also happen while still alive.
This is where indulgences come in.
Indulgences, whether partial or plenary, are gained through specific works and actions that are designated by the Church. These
include works of devotion, penance, and charity. They are things that direct our thoughts and actions to God and by doing so, turn our
minds away from sin, thus helping to remove those attachments to sin that we have. There are numerous ways to gain indulgences that
can be found online and elsewhere and are too many to list here. What is also required to gain the indulgence, in addition to whatever
the specific indulgence might be, is to go to confession within a week on either side of when the indulgence is done, receive
communion in the state of grace, and to pray for the intentions of the Holy Father.