I understand this is the teaching, I just don’t see how it adds up logically with the idea that Purgatory is so we, personally, can expiate or pay for or clean up from sin, and then turn around and say that another human here on Earth can actually do or “fill up” what Jesus’ sacrifice could not or did not do in eternity (here on earth is different, as we are His body in the present age). An Eternal Perfect being took on all punishment for sin, all condemnation, past, present, and future. He took on actual temporal punishment, but its effect is eternal, because He Himself is eternal.
Remember what Paul said in colossians:
Colossians 1:24 ►
Now I rejoice in what I am suffering for you, and I fill up in my flesh what is still lacking in regard to Christ’s afflictions, for the sake of his body, which is the
*The fact is, if we are truly sorry, we will see the need and the propriety for restitution. Not just monetary, physical restitution for broken windows, but psychical, spiritual restitution for broken souls.
The people we’ve hurt, the people we’ve refused to bless, the people we’ve refused to give ourselves to and to give Christ to, the incredible opportunities that we’ve missed because we were lazy and slothful, proud and arrogant. Those memories will burn more than any physical fire when our souls encounter the fiery love of Christ in the Holy Spirit. All those missed opportunities we willfully refused. It’s one thing to miss opportunities for imperfections and faults, another thing to sin deliberately by not giving ourselves. It might not be mortal sin, but we are not only wounding ourselves, but we are wounding the souls who depend upon us.
Now are we paying for our sins? No, they are paid for. And the only way we can make restitution is because the life of Christ through the Holy Spirit has been poured out in us so that through our sufferings Christ’s glory can be reproduced in us. But there’s no short cut. Hebrews says that Christ, though a Son, learned obedience through suffering. Why did He suffer? That His human nature could learn obedience and impart that human nature to us through the flesh and blood in the Eucharist, the body and blood of Christ. When we receive that human nature of the eternal Son of God and historical Son of Man, we are enabled to learn obedience through suffering. There’s no other way to learn obedience.*
And further by John Vianney:
saints.sqpn.com/catechism-on-suffering-by-saint-john-vianney/
There are two ways of suffering — to suffer with love, and to suffer without love. The saints suffered everything with joy, patience, and perseverance, because they loved. As for us, we suffer with anger, vexation, and weariness, because we do not love. If we loved God, we should love crosses, we should wish for them, we should take pleasure in them. . . . We should be happy to be able to suffer for the love of Him who lovingly suffered for us. Of what do we complain? Alas! the poor infidels, who have not the happiness of knowing God and His infinite loveliness, have the same crosses that we have; but they have not the same consolations. You say it is hard? No, it is easy, it is consoling, it is sweet; it is happiness. Only we must love while we suffer, and suffer while we love.