Hi, Suzanne —
First of all, Jesus was speaking to one person who was already suffering on the Cross. That suffering may have served his final purification.
Secondly, Purgatory is not a separate place from Heaven. If you want to call it a place at all, it's a suburb of Heaven or the mud room where you wipe your feet and get cleaned up before you walk into the rest of house.
Purgatory is really a condition of purification that is accomplished by being in the presence of God. It is God's love that burns away the remaining selfishness which is caused by our sin. Every time we sin, we effect our soul by feeding the flesh or the self. The purpose of Purgatory is to finish the job of sanctification that is not completed in our life time. Sins are forgiven when we repent and the relationship with God is immediately restored but the damage we do to ourselves by feeding our sinful desires often take times time to heal. That's why most of us repeat the same old sins over and over.
The doctrine of Purgatory is actually very simple. It's a place or condition for those who are saved and who die in a state of friendship with God and it involves suffering. We can assist those suffering during this purification by our prayers just as we can pray for anyone who is living that God will sanctify them. That's really it.
Now throughout the centuries we've used different models to explain this.
In the Middle ages, theologians used or relied on a punishment model but it wasn't punishment based on wrath, rather it was the punishment of a father on his son, for his own benefit. Like any model we use to explain a Mystery of Faith, it had its problems and limitations.
I prefer to use the healing model. Purgatory is a Holy Ghost Hospital, where the Love of God heals us. The pain isn't punishment. It's a healing pain or growing pain and there is also much joy in Purgatory because the person knows they are being perfected and being drawn closer to God.
It's like a runner at the end of Marathon. He can see the finish line. He knows he's closer and closer with each step and he knows he will win the his race but it is all God's Grace that does the work in him, and for those being purified in them.
Now as to the Saints, I will keep it brief.
Saul was summoning a witch and committing sorcery to know the future. (1 Samuel 28:8-14)
When we pray to a saint, it's no different that asking any living saint to pray for us, with the one difference being that the soul is in Heaven (or even Purgatory) praying for us, it is not concerned with themselves but with doing God's will. For that reason, that person is freer to pray according to God's will for us. All Christians are called to pray for each other and with one another.
- We don't stop being Christians when we get to Heaven right?
Hebrews 12 makes it clear that the Church in Heaven and on Earth are connected. So doesn't Revelation 5:8. These people in Heaven aren't dead but alive in Christ, otherwise how could Moses and Elijah appear with Jesus on the Mount of Transfiguration to Peter, James, and John. (Matthew 17:1-13)
Even in the account of Herod killing the babies at the time the Magi, we read the Rachel, the Matriarch, was weeping for her children so those who physically die in faith, remain connected to the living believers. (Matthew 2:16-18)
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