We have lots of ways, as Catholics, to obtain indulgences. For example, a plenary indulgence is available every time we make the stations of the cross, or adore the Cross on Good Friday (I'll include some more below.)
So what is an indulgence?
An indulgence is the "remission"--the eradication, wiping away--of temporal punishment due to sin. What is "temporal punishment due to sin"?
Well, the Church distinguishes between "eternal" and "temporal" punishment due to sin. The eternal punishment due to sin is damnation. We deal with that through turning back to God; and while God can forgive anyone, and we believe he does forgive all who genuinely turn to him, the normal way we seek that forgiveness is to confess our sins sacramentally. (What about people who don't believe in this sacrament? I ask, do they believe in God and in confessing sin? Then God works with them where they are.) Of course, there's always the extreme option of making a perfect act of contrition, but really, if you have access to a priest, why play that game? Go to confession and have no fear!
So what is temporal punishment? That is the punishment that precedes eternity--embraces both the lived consequences of sin, as well as the purification that our souls may require upon departing this life into eternity. "Punishment" is used here in a broad sense. It doesn't necessarily mean some penalty God decrees; it can simply mean the consequences of sin.
So, for example, we're not saying that every time we sin, there's a verdict handed down, in which we earn some penalty; it doesn't mean, as so many think, that God sends us trouble in this life.
Punishment in this sense can simply mean that our sins have consequences, and even if we are forgiven of an eternal punishment, we still have to deal with those consequences.
So, for example: your sister may forgive you for stealing her book and ruining it. But that doesn't change the fact that justice calls for you to make some reparation: go buy her a new book, or make it up in some other way.
Another example: a person who tends to lie--a lot--can be forgiven of the eternal punishment; yet the effect of a habit of sin remains; and so that person must work to change his or her habits and appetites.
This can happen in this life, or in the life to come: in other words, our experience in purgatory.
When we receive an indulgence, it can be "partial" or "plenary"--the latter meaning, full or complete.
And when we obtain such any indulgence, we can keep it for ourselves, or else offer it to God on behalf of souls now in purgatory.
Now, some people find this distasteful or else misunderstand it.
An indulgence is not the "forgiveness of sins": that is obtained through confession of sin in the sacrament of reconciliation. For an indulgence to be plenary there has to be sacramental confession of sins.
So an indulgence is not a "get out of jail free" card; it goes to those who have already "gotten out of jail" the usual way.
So what is an indulgence?
Think of it this way: it is a fruit of God's mercy, it is a concrete way God gives to us, and applies to our concrete lives, that mercy which poured out into the world at the Cross--and continues to be available freely to all who need it.
Of course, someone will latch onto the fact that we perform a work: so the complaint is, we're being saved by works. But again, an indulgence is not "salvation." To put it another way, those who aren't saved--or in the process of being saved--cannot benefit from them!
Someone who is not in a state of grace cannot benefit from an indulgence! Only someone already on the path of salvation--someone who is "saved" (or being saved, since we believe that is not complete until we finish our lives cooperating with grace)--can benefit from an indulgence.
So the work of an indulgence is not to "gain" salvation, but to respond to it. We do these works of charity or prayer or devotion in response to God's salvation--not to obtain it.
The point of indulgences is to make concrete the path of conversion, and to move us along to greater conversion. So they only "work" to the extent we actually, well, "convert."
Hence an indulgence only is "plenary" when we go to confession, go to communion--meaning we're united with the Son of God sacramentally--we pray for the pope's intentions--meaning we're united with the Lord's Church on earth--and we have no attachment to venial sin.
And if we don't meet all the conditions? Then the indulgence is "partial." Meaning: we gain a partial lessening of the need for purification.
Think about it: what is it, exactly, that we're dealing with? We're dealing with the effects of sin on our lives. The man who is a glutton needs not only to confess that sin--and be forgiven eternally--but also to change his life so he is temperate in his appetites. If I--er, that man--enters eternity with gluttonous appetites, that disordered state must be fixed or else I--um, I mean that other guy--cannot be perfectly happy in heaven.
So this business of correcting or purifying us of all the consequences and effects of sin is an additional gift of God!
How would you like to spend eternity with a nagging source of unhappiness? An itch you cannot scratch? A thirst you cannot quench? Does that sound like heaven? Might sound more like hell.
God does not want anyone to spend eternity with such unhappiness, but some have made their choice (the fallen angels for certain, and anyone else who may be in hell as I write). So for those whose choice is made, it is, sadly, too late. But for all others, God seeks a multitude of ways to win us to heaven.
And for those who are moving toward heaven--in the imperfect, bumptious way most of us tend to make that pilgrimage--God provides endless ways of getting ready for heaven. After all, he could simply give us no preparation at all, until we arrive at the gates--and then we get ushered into the "fixing" room called purgatory. And then, we might--as we undergo whatever it takes to make us completely ready for heaven--complain, "God, why didn't you give me ways to deal with this along the journey?"
Well, that's just what God has done. Every day we can be working on our conversion. What did St. Peter say in Scripture? "Work out your own salvation with fear and trembling"--yet it remains true what St. Paul said: "you are saved by grace." It is God's grace that animates and guides the entire enterprise, including whatever degree of good motives and desire for conversion we ourselves experience.
To obtain the indulgence, we not only do the action described, but we also go to confession, receive holy communion, pray any prayer for the pope’s intention, reject all attachment to sin.
So an indulgence--to the extent it "works"--only works because we're cooperating with God's grace. It is not mechanical or magical. God is not mocked! Do you suppose God does not see? If we "go through the motions," yet do not seek sincerely to be changed people, how can we imagine an indulgence will work for us?
But we can be a little more positive about it. If we go to the stations of the cross, or we pray the Rosary, or we adore the Cross on Good Friday, or do any number of other things that have indulgences attached to them--how can we completely shield ourselves from at least some good effect? If you dive into a pool, you will get wet; why, even if you sit near a pool, you will have a hard time avoiding getting some water on you. And if you spend time in prayer and works of charity, it's hard to imagine how anyone could avoid being at least somewhat changed.
Hence the logic of a "partial" indulgence: it will help you at least partially!
Now, what other questions remain?
Does it bother us that indulgences attach to specific works or prayers?
Think of it this way. Suppose God said, "I have good news! You can, by works and acts of charity and prayer, be changed so that all need for purgatory is behind you!"
And we say, "Wonderful! What are these works and acts of charity?"
And God said, "I'm not going to tell you!"
Not so nice, eh?
Instead, God gives his Church "the power of the keys" (See Matthew 16): and thus the Church specifies these works and prayers. Mighty helpful, is it not, to have concrete and specific steps to take for your own spiritual well being?
Does it bother us, or require explanation, that we "apply" a plenary indulgence to the souls in purgatory? Does it not make perfect sense? What we need is conversion--and what is a more powerful way to experience change than to expand our hearts through charity? To know what a plenary indulgence is--and then to give it away--what is more charitable? More Christlike? "He who knew no sin, became sin for us."
Our goal ought to be to breathe our last and find that we bypass purgatory because we don't need it. We've received our purification and making-ready in this life. Upon arriving at that moment, who would pause to say, "hrm, I seem to recall giving away all my plenary indulgences, so how did this happen?" We will be too busy plunging into the bliss the Blessed Trinity.
From the Handbook of Indulgences, a partial list of plenary indulgences (please don't expect I will have all the answers about these):
> Visit the four Patriarchal Basilicae in Rome.
> Receive the papal blessing, either from the pope himself, in Rome, or via radio or TV, or from a bishop when he is able to do so.
> Visit a cemetery and pray for the dead between November 1-8.
> Adore the Cross in the solemn liturgy on Good Friday.
> Pray a specific prayer before the crucifix on Fridays during Lent.
> Participate in solemn eucharistic rite that concludes a Eucharistic Congress.
> Spend at least 3 days of spiritual exercises on retreat.
> Act of Reparation to the Sacred Heart on the Solemnity of the Sacred Heart.
> Act of dedication to Christ the King on that feast.
> At the moment of death, by praying--simply praying! (See Handbook, n. 28)
> Participating in a mission and being present for its solemn conclusion.
> First communion, receiving or assisting.
> Priest's first Mass with a congregation, for the priest and those who take part.
> Rosary recited in church, oratory, in family, a religious community or "pious association." Five decades, without interruption, suffice.
> Jubilee celebration of a priest's 25th, 50th and 60th anniversary of ordination, for the priest and faithful.
> Visiting a church where a Diocesan Synod is held.
> Praying a particular prayer on Holy Thursday or Corpus Christi. (Seems to be "Tantum Ergo" but the translation doesn't match.)
> Te Deum on January 31.
> Veni Creator Spiritus on January 1 and Pentecost.
> Stations of the Cross.
> Visit a church on its titular feast day, or on August 2.
> Visit a church or oratory on All Souls Day--this is only for the souls in purgatory.
> Divine Mercy devotion--I cannot recall the details.