Purgatory And The Communion Of Saints
If you die in the love of God but possess any 'stains of sin', such stains are cleansed away in a purifying process called purgatory. These stains of sin are primarily the temporal punishment due to venial or mortal sins already forgiven but for which sufficient penance was not done during your lifetime. This doctrine of pugatory, reflected in Scripture and developed in Tradition, was clearly expressed in the Second Council of Lyons (AD 1274)
Having passed through purgatory, you will be utterly unselfish, capable of perfect love. Your selfish ego - that part of you that restlessly sought self-satisfaction - will have died forever. The "new you" will be your same inner self, transformed and purified by the intensity of God's love for you.
Besides declaring the fact of purgatory, the Second Council of Lyons also affirmed that " the faithful on earth can be of great help" to persons undergoing purgatory by offering for them "the Sacrifice of the Mass, prayers, almsgiving, and other religious deeds".
Implied in this doctrine is the bond of oneness - called the Communion of Saints - that exists between the Poeple of God on earth and those who have gone before us. Vatican II focuses on this bond of union by saying that it "accepts with great devotion the venerable faith of our ancestors regarding this vital fellowship with our brethren who are in heavenly glory or who are still being purifed after death" (The Church, 51)
The Communion of Saints is a two-way street. In the section quoted above, Vatican II points out that just as you on earth can help those who undergo purgatory, those in heaven can help you on your pilgrimage by interceding with God.