While I have the utmost respect for the great Saint, is seems to be to the teaching of the Church that all sins, regardless of type or number, will always be forgiven by God (whether through Baptism or Confession), so long as the penitent has sorrow for his sins, and a firm intention to sin no more.
I don't think that's what St. Alphonsus means. I think that his intent is more along the lines of the proper understanding of Catholic predestination. There's no sense in which God's Mercy can ever "run out" or reach some kind of limit.
And, with the same respect for St. Alphonsus, and while I understand what he was trying to accomplish, the stories about a five-year-old committing one mortal sin and being sent to hell do not really paint a very nice picture of God. It almost creates this caricature that God is just lying in wait for that mortal sin so He can strike the poor kid down. You completely lose any sense of God's Mercy with this. St. Alphonsus was speaking to those who just keep sinning and sinning and sinning, thinking that in the end they'll just stop. That was a recurring theme of his. But at the same time we do NOT want to create this kind of caricature of Our Merciful Father. If such a thing actually happened, it needs to be related with the appropriate clarifications. God knows how bad the state of that soul would have become had He let him continue living and snatching him so early was certainly as much an act of God's Mercy as of His Justice. Every act of God's is always both perfectly merciful and perfectly just at the same time.
'He who receives pardon, says St. Augustine, is pardoned through the pure mercy of God; and they who are chastised, are justly punished. How many has God sent to Hell for the first offense? St. Gregory relates, that a child of five years, who had arrived at the use of reason, for having uttered a blasphemy, was seized by the Devil and carried to Hell. The divine Mother revealed to that great servant of God, Benedicta of Florence, that a boy of twelve years was damned after the first sin. Another boy of eight years died after his first sin, and was lost. You say: I am young; there are many who have committed more sins than I have. But is God on that account obliged to wait for your repentance if you offend Him?'
St. Alphonsus Maria de Liguori
From the above link.
I don't lose any sense of God's mercy from this Ladislaus, and the saints had good reason to relate this, no? A mortal sin is a terrible thing, one or many. I think the story shows how terrible a sin blasphemy is, and how dreadful, and how important it is children be raised to love God and fear sin.
God decides, quickly or slowly, in one way or another, it is always the perfectly good decision. The angels never had a second chance after the first sin, and never will. People try to judge God's decisions. Apologists try to explain away His decisions and give people the feeling the can do that, when the can't. That is the mistake.
Blessed Virgin pray for us.
What Ladislau is explaining to you will be further clarified by this:
"
Before all decision to create the world, the infinite knowledge of God presents to Him all the graces, and different series of graces, which He can prepare for each soul,
along with the consent or refusal which would follow in each circuмstance, and that in millions of possible combinations ... Thus, for each man in particular there are in the thought of God, limitless possible histories, some histories of virtue and salvation, others of crime and damnation; and God will be free in choosing such a world, such a series of graces, and in determining the future history and final destiny of each soul. And this is precisely what He does when among all possible worlds, by an absolutely free act, he decides to realize the actual world with all the circuмstances of its historic evolutions, with all the graces which in fact have been and will be distributed until the end of the world, and consequently with all the elect and all the reprobate who God foresaw would be in it if de facto He created it." [The Catholic Encyclopedia Appleton, 1909, on Augustine, pg 97]
In other words before a man is conceived, God in his infinite knowledge has already put that person through the test with millions of possible combinations and possible histories, some histories of virtue and salvation, others of crime and damnation;
along with the consent or refusal which would follow in each circuмstance (of millions of possible combinations!!!) and God will be free in determining which future history and final destiny He assigns each soul.
The idea of salvation outside the Church is opposed to the Doctrine of Predestination. From all eternity God has known who were His own. It is for the salvation of these, His Elect, that Providence has directed, does direct, and will always direct, the affairs of men and the events of history. Nothing, absolutely nothing, that happens, has not been taken into account by the infinite God, and woven into that tapestry in which is written the history of the salvation of His saints. Central in this providential overlordship is the Church itself, which is the sacred implement which God devised for the rescuing of His beloved ones from the damnation decreed for those who would not. (Mt. 23:37).
The Doctrine of Divine Election means that only certain individuals will be saved. They will be saved primarily because, in the inscrutable omniscience of God, only certain individuals out of all the human family will respond to the grace of salvation. In essence, this doctrine refers to what in terms of human understanding and vision, is before and after, the past, the present, and the future, but what in God is certain knowledge and unpreventable fact, divine action and human response.
Calvin and others have made the mistake of believing that these words mean that predestination excludes human choice and dispenses from true virtue. Catholic doctrine explains simply that the foreknowledge of God precedes the giving of grace. It means, further, that, since without grace there can be no merit, and without merit no salvation, those who will be saved must be foreknown as saved by God, if they are to receive the graces necessary for salvation.
Thus, what is the meaning of this election? That from all eternity God has ordered the events of history, so that His Elect might have the grace of salvation. And how do they know of this election? By the fact that they are in the Church, through no deservingness of their own? They know of no reason why God should bestow this grace, the knowledge of the truth, and the willingness and power to believe it, upon them, while others, who seem more worthy, go without it. As regards His Elect, not only has God determined to bestow necessary grace, but also, all His actions in the world must be seen as part of His salvific plan. In a word, nothing that He does is unrelated to the salvation of His Beloved Sheep. Human history, apart from the glory of Holy Church, and the salvation of the Elect, and the punishment of the wicked, has little importance for almighty God. Yet, all these purposes are only a part of the manifestation of His glory.
The Doctrine of Predestination is that almighty God from all eternity both knew and determined who would be saved, that is, who would allow Him to save them. He would be the cause of their salvation, and, as there is no power that can even faintly obstruct or withstand Him, there is no power which can prevent His saving whom He wishes, except, of course, the man himself.