Imagine going on a spelunking trip with some friends. Deep inside the cave is pure darkness. There is a confusing maze of passages and deep holes to fall into. Your flashlight is your life. Suddenly, you feel the floor and the walls of the cave tremble. Rocks begin crashing against rocks and you realize there has been a cave-in. As your group regains composure it becomes evident that leaving the way you came is not an option. The search for an exit begins.
As time goes by, batteries begin to fail. Lights become dim. Anxiety grows. You feel there must be an exit nearby, but the lights go out before it is found. Trapped in complete darkness, you can only wait for rescue. Your deepest desire is to leave the darkness and embrace the light.
After days of increasing desperation, you hear the sounds of rescuers. The ceiling of the cave suddenly opens. It is midday. The sun is high and its rays pierce the darkness as it streams through the new hole in the cave. You immediately cover your eyes in anguish. You are distracted from the joy of being rescued by the pain inflicted by the light. The light you so desired is now too much to behold. It is impossible to fully embrace your freedom until you are able to accommodate the light. There must be a period of adjustment. You must become completely detached from the darkness before your eyes can fully see without pain.
This is why Catholics pray for those in Purgatory. We recognize that they must endure the painful process of complete detachment from this life of sin before they can fully embrace the light of Christ. Although they are on their way to Heaven, they must be fully adjusted to the Light before entering. The Rescuer has reached them. They are open to God and on their way to the Beatific Vision. They desire to be with God, but they must be prepared and perfected beyond what they were in this life. We pray for them during this painful state of transition, just as we would pray for someone suffering in this earthly life.
This explains why those in Purgatory are called “The Church Suffering.” We in this life are called “The Church Militant” because we are still here fighting the good fight. Those already in Heaven are called “The Church Triumphant” for obvious reasons. These are three parts of one Church. The Church is one Body, no matter where it is located. We in the Church are told to pray with and for one another. So, we pray for the suffering in this life. We also pray for those who suffer the process of purging. They are our brothers and sisters in the Lord. We support them.