- The reason that one does not have to get a plenary indulgence to remove all temporal punishment is that indulgences are not required, only penance, also note that these are satisfactions not infusion of grace. Read what the Catechism states in 1471:
""An indulgence is a remission before God of the temporal punishment due to sins whose guilt has already been forgiven, which the faithful Christian who is duly disposed gains under certain prescribed conditions through the action of the Church which, as the minister of redemption, dispenses and applies with authority the treasury of the satisfactions of Christ and the saints."81 "
Then it is explained how that purification occurs before death:
“A conversion which proceeds from a fervent charity can attain the complete purification of the sinner in such a way that no punishment would remain.83
83 Cf. Council of Trent (1551): DS 1712-1713; (1563): 1820.”
Then in Canon 30 from the Council of Trent you can see, on satisfaction for our sin by penance:
Chapter 14 [807] … as well as satisfaction by fasting, almsgiving, prayers, and other devout exercises of the spiritual life, not indeed for the eternal punishment, which is remitted together with the guilt either by the sacrament or the desire of the sacrament, but for the temporal punishment [can. 30], which (as the Sacred Writings teach) is not always wholly remitted, as is done in baptism, to those who ungrateful to the grace of God which they have received, “have grieved the Holy Spirit” [cf. Eph. 4:30], and have not feared to “violate the temple of God” [1 Cor. 3:17]. Of this repentance it is written: “Be mindful, whence thou art fallen, do penance, and do the first works” [Rev. 2:5], and again: “The sorrow which is according to God, worketh penance steadfast unto salvation” [2 Cor. 7:10], and again: “Do penance” [Matt. 3:2; 4:17], and, “Bring forth fruits worthy of penance” [Matt. 3:8].
[Denzinger 840] Can. 30. If anyone shall say that after the reception of the grace of justification, to every penitent sinner the guilt is so remitted and the penalty of eternal punishment so blotted out that no penalty of temporal punishment remains to be discharged either in this world or in the world to come in purgatory before the entrance to the kingdom of heaven can be opened: let him be anathema [cf. n. 807].
The Catholic teaching (dogmas) are that those in purgatory are there due to being just and because of temporal punishment. Note the purpose “satisfactory works have for their object the removal of the temporal punishment still due to sin”.
Catholic Encylopedia
In Christ’s work of redemption merit and satisfaction materially coincide almost to their full extent, since as a matter of fact the merits of Christ are also works of satisfaction for man. But, since by His Passion and Death He truly merited, not only graces for us, but also external glory for His own Person (His glorious Resurrection and Ascension, His sitting at the right hand of the Father, the glorification of His name of Jesus, etc.), it follows that His personal merit extends further than His satisfaction, as He had no need of satisfying for Himself. The substantial and conceptual distinction between merit and satisfaction holds good when applied to the justified Christian, for every meritorious act has for its main object the increase of grace and of eternal glory, while satisfactory works have for their object the removal of the temporal punishment still due to sin.
Pohle, J. (1911). Merit. In The Catholic Encyclopedia. New York: Robert Appleton Company.
newadvent.org/cathen/10202b.htm
- The removal of the temporal punishment still due to sin is not referring to original sin consequences nor to granting any preternatural gifts (bodily immortality, integrity, and infused knowledge) that we never received but the Adam and Eve had, but what results from personal actual sins. One should not confuse the two effects and differences: one ancestral and the other personal.
- One cannot deny that God is omniscient thus knew the event of the Fall and expulsion from paradise and subsequent event of the birth of Abel after Genesis 1:28 blessing to be fruitful and multiply.
- Satisfaction for sins not infusion of grace occurs in purgatory. Father Edward McNamara, professor of liturgy at the Regina Apostolorum university, writes:
In the case of the deceased in purgatory any benefit is received passively, since the soul is no longer capable of performing new meritorious acts. While such a soul is already saved, it cannot increase in sanctity but only purify those imperfections which impede its definitive entrance into glory.
A living person, however, is still capable of growing in sanctifying grace. And so a Mass offered for a person already in God’s grace has the effect of offering a gift of increased grace which the person may willingly receive in order to become more Christlike.
ewtn.com/library/Liturgy/zlitur176.htm