On Purgatory
Someone asked me about how Purgatory relates to Christ's sacrifice, and since I really don't have anything about Purgatory listed on here I thought would post my reply:
In short, there are two separate issues that are involved in an understanding of purgatory, especially as it relates to Christ's sacrifice. The issue of forgiveness, and of consequences. I may forgive someone for stealing my car, but they still need to return my car or make some type of amends. Although it may be difficult to separate these two things, it is necessary in order to understand the doctrine of purgatory.
Sin then, has two types of consequences. Eternal consequences, which is eternal death or hell; and temporal consequences, such as lung cancer from smoking or the example I gave above. Christ offers us forgiveness for all of our sins, and His death pays for the eternal consequences, giving us the grace needed to spend eternity with Him in Heaven.
Our relationship with him is not merely a one way street though. He wants more from us than just an acknowledgment that He exists, and that we're ok with Him sacrificing His life for us. (Even the demons believe...) He wants us to play an active part, to "work out" our salvation. The bible speaks of salvation being a thing of the past, present, and future.
Christ has given us several ways in which we are able to play an active part in our relationship with him, and in his work of grace. Since we still have temporal consequences for sin, one of these ways is purgatory. It is the way that Christ enables us to enter heaven even though we die with sin consequences that have not been amended for yet. (Of course, Christ provides other avenues which we can make amendments while we are still alive, but I will not go into that now.)
Purgatory then, is God's "refining fire." It is God's way of completing the purification process that was made possible through Christ, so that we may come to see God in complete purity; without spot or blemish. Christ has given us clean clothes so that we can attend the wedding feast... purgatory is like the changing room where we put them on before entering.
When we pray for people in purgatory, it is the same as if we were praying for friend who was going through a rough time in their life: We are asking for God to give them grace and allow their time to pass quickly.
Purgatory then, was never meant for those who have rejected Christ, it is an avenue of grace, a "refining fire" only for those who have accepted Christ and are on their way to heaven.
If you're looking for more depth, then you may find these two links helpful:
http://www.catholicnewsagency.
http://scripturecatholic.com/